Uuuughhhh I've spent several hours doing mental gymnastics to make the Tribe/Children of the Watch make sense from a worldbuilding perspective, particularly regarding the facts that only one person -- the designated bounty hunter -- is allowed outside of the covert at a time and the way Din has so much blind faith that his beliefs and those of his cohort are the norm despite the Tribe being described "as a cult of zealots" by mainstream Mandalorians. It begs questions of how the Tribe/Children of the Watch is structured just like, administratively -- such as whether they were merely an arm of a political movement or are a legitimate religious sect in its own right -- how many people adhere to their beliefs, and how it survived both the demise of Death Watch and the wider Mandalorian purge. It's exhausting, but I think I've come up with something fairly plausible. Or maybe not. We'll see.
Coverts in Mando era (around 9 ABY) have to be relatively small by design if the whole community are going to be supported primarily by the income of just one guy, and screenshots of the end of "The Sin" and stills of s3 episodes support this. So lets say that theres only a few dozen Mandalorians per covert. Let's say average 20-40 people, including children. Almost all of these children are foundlings, because resources are tight and we can imagine nobody's really been going hard at procreating since it's only been like, four years since Operation Cinder and the Mandalorian Purge.
However, what we do know is that Din is absolutely aware that there are more Mandalorians out there than just his covert. We can interpret this several ways. Going by what we learn in the first two seasons of The Mandalorian, it'd be easy to just assume this small group of people is all Din knows, and was merely told that there are lots of other Mandalorians out there who act like him and believe in the same doctrine. That the covert system, with only one member out and about at any one time, has always been the norm in his religion. That would explain his firm belief that all Mandalorians abide by the helmet rule, but it wouldn't necessarily explain how notorious Mandalorians are in the wider galaxy (the number of Mandalorians running around at any one time would always equal the number of coverts in existence), nor the way clan membership still holds importance in his experience of Mandalorian culture. Why would names or clan loyalty mean anything if your entire community was made up of essentially just 39 other people?
This all makes a lot more sense once we learn in S3 that no, the covert system wasn't always the norm, Din was raised on Concordia, and that the Tribe was based there up until Mandalore was glassed. We can then assume coverts were formed specifically as a response to the Purge. I'm imagining that coverts came out of some sort of already pre-established administrative unit that are separate from clans (since several are represented in Din's covert), that were first established when the entire Tribe/the Children of the Watch was situated on Concordia.
As of Mando S3, there's still no clear answer as to how many coverts were or still are scattered throughout the GFFA. Could be a few, could be thousands, we just don't know. So we don't know how many Tribe members there are. We do know that Mandalorians in general are absolutely rare when taken in the totality of the galaxy, especially after the Purge; Din doesn't seem to have met another one organically on his travels, or at least not one not affiliated with the Children of the Watch, before Bo-Katan and her crew. But we do know that at one point before there were enough Mandalorians roaming around the GFFA that people know to call Din one on sight, and Din doesn't question this fact at all. It could be just that the reputation/legend of Mandalorians has spread far and wide, but nobody Din interacts with seems particularly shocked to actually be meeting one in the flesh -- another thing Din doesn't really question.
Now, Din may be sheltered, but he's not dumb. I'd even reckon he's pretty smart, albiet a little tunnel-visioned. The fact that he gets recognized as a Mandalorian but is not treated as anything more than a curious oddity leads me to think that the Tribe/Children of the Watch may actually be fairly sizeable -- especially since they're a known minority to the surviving mainstream Mandalorians -- and Din probably was able to get an idea the full scope of the movement's size while living on Concordia as a child. The Tribe/Children of the Watch being larger than we'd most likely imagine probably only further reinforced for Din that all Mandalorians are just like him; unlike nearly every fundamentalist religion irl, he has no concept of "us" versus "them" except for "Mandalorian" and "Not Mandalorian". He has no conception that there might be people out there who purport to be Mandalorian but aren't doing it the "right" way. We can assume that in his mind, everybody who looks like him IS like him, so to speculate even further, perhaps he was even told that there were other tribes out there as well -- since the Tribe is canonically likened to a clan -- of similar size that make up "the nation," which could be different in their specific practices but still follow the core orthodox tenets of the Way of the Mand'alor. (Something something compare it to the twelve tribes of Israel slash maybe different Jewish ethnic divisions if you want to get biblical about it.) Whether this actually has any basis in the historical traditional Mandalorian martial religion or is just a piece of liturgical propaganda invented by Death Watch members is anybody's guess, but it would explain away the fact that Mandalorians are so recognizable in the GFFA to those members of the Tribe/Children of the Watch who don't know anything else but what their sect taught them.
And speaking of Death Watch. Considering what we see of Bo-Katan's arc in S3, we can reasonably assume that by Mando era the Tribe/Children of the Watch most likely practices a form of Mandalorian religion that's probably fairly indistinguishable from other ultraorthodox sects (given that they exist, though it most certainly would have its own quirks considering its origin). Other than self-preservation, the Tribe seems to be fairly apolitical when it comes to day-to-day practice. But that doesn't erase the fact that the Children of the Watch itself originally started out as a sect/cult created by followers of the Death Watch movement and perpetuated by their descendants.
I don't really have any problems with this from a narrative or worldbuilding standpoint. I actually think the implications are super interesting, and it gives Bo-Katan a reason to be so biased against Din's beliefs upon first meeting. Narratively, the idea that a subset of a reactionary political faction used the traditional Mando religion as tool to support their cause rules actually, and it makes sense. Death Watch members creating a new orthodox sect that aligns with their movement's political goals is a clever way to establish an ever-growing pool from which to draw pre-indoctrinated recruits for their eventual coup d'etat against Satine Kryze's New Mandalorian government. That explains why the Tribe/Children of the Watch are so keen on taking in foundlings (children are the future, after all) and on keeping their members' individual identities and whereabouts secret; ba'slan shev'la -- strategic disappearance -- becomes doctrine instead of simply a Mandalorian battle tactic due to the covert nature of the founders' political aims. But the fact that Din doesn't even know what Death Watch even IS is something of a troubling issue, especially since he was taken in at the height of their political movement and was probably around for their coup/the Siege of Mandalore. It implies that the Tribe/Children of the Watch, despite being affiliated and born out of the Death Watch political movement, that by 19 BBY it was separate enough that they weren't outright politically indoctrinating their converts.
It sort of makes sense, since keeping the CoW/Tribe nominally separate from the Death Watch movement proper provides plausible deniability regarding their involvement in counterrevolutionary political organizing under Pre Viszla. Pre was the governor of Concordia, remember, and if anybody got wind of a growing separatist community of Mando traditionalists based there, he could simply explain it away as Mandalorians exercising their religious freedom on the Designated Mandalorian Traditionalist Planet. That the revived political arm of Death Watch would then recruit highly-trained fighters from the CoW's Fighting Corps would conveniently not be mentioned.
So, getting back to it -- exactly how big is the Tribe/Children of the Watch? According to canon, what remained of Death Watch and its followers after the Mandalorian Civil War that resulted in Satine Kryze's rise to power were exiled to Concordia around 39 BBY, so a little under twenty years before the start of the Clone Wars. If you want to bring some of Legends canon into this, they formed about two decades before that as a traditionalist reactionary group in response to Jaster Mereel publishing his reformist supercommando codex. So by the time of their banishment, they probably had a sizeable following that would have certainly included ultrareligious, ultraorthodox members, who we can assume formed the founding members of the Tribe/Children of the Watch. Because of their unshakable devotion to the Way of the Mand'alor, they would have almost certainly bowed to Pre Viszla by the time he came around shortly after Satine's rise to power and began reorganizing the Death Watch political movement, since he was the holder of the Darksaber at the time. The Mand'alor is the sole ruler of the Mandalorian nation, so it would stand to reason that they would also be the figurehead of the traditional Mando religion.
If word somehow got around through underground channels that the holder of the Darksaber was based on Concordia, it would be plausible for the Tribe/Children of the Watch's membership to grow incredibly rapidly between 39 BBY and 19 BBY, right before the the political arm of Death Watch functionally died. Considering what we know of Din's origin story, Death Watch members were actively going into conflict zones and scooping up war orphans left and right all the way through the Clone Wars and placing them with the Children of the Watch. Not only that, it stands to reason that the CoW probably also gained a LOT of adult converts both before and during the Clone Wars, since not only were there a bunch of "Old Mandalorians" hanging around the galaxy in diaspora, but there were probably a bunch of traditionalist Mandos on Mandalore proper who felt alienated by Satine's New Mandalorian government, whether it be for religious/ideological reasons or simply because she didn't hold the Darksaber, and thus technically not the Mand'alor.
So, if we assume in good faith that, alongside being Death Watch's main propaganda and recruitment tool, the Children of the Watch over the course of those twenty years had turned into a legitimate semi-autonomous religious movement whose main draw is that it has the direct patronage of the current Mand'alor with aims to overthrow the current heretical government, it could have had some insanely explosive growth during that time. Like I'm imagining almost 10,000 members or more, at least half of which were probably children and those in noncombatant roles, and only a very small fraction of which might have been actually formally tied to the original Death Watch. They would fight for Mand'alor (and thus Death Watch) when called upon, sure, but it would be a religious obligation rather than necessarily a political one. Heeding the Mand'alor's call is baked into the Mandalorian Creed; all traditional Mandos from any orthodox tradition would have an obligation to do so. This would account for the sheer amount of manpower Death Watch had access to. Religious recruitment is always more effective on a large scale than political organizing. However, from the outside it would all appear as a monolith -- the Death Watch movement.
This sort of short-term conversion boom isn't unheard of in new religious movements irl; between 1974 and 1984, spiritual guru Baghwan Shree Rajneesh gained tens of thousands of followers, at least 7000 of which were dedicated enough to live on his ashram/proto city/converted ranch in rural Oregon, a population which swelled to 15,000 during times of pilgrimage. And if you want to trust self-reported numbers, the LDS church purports to have gone from 6 to 20,000 converts in the first 12 years of its existence. Concordia isn't huge, but it is a whole planet that's basically a warren of beskar mines. You could probably hide the population of a small town scattered across it easy. And a legitimate religious community that size would have more than enough momentum to continue on its own without its founders (as evidenced by the fact that the both the IRL Rajneesh movement and the LDS church are both going strong to this day) or the political movement that provided most of its momentum during its heyday. Add the fact Bo-Katan lost control of Mandalore to clans that allied with the Empire fairly shortly after the end of the Clone Wars, and you have a recipe for even more radicalized converts looking to escape mainstream Imperial-governed Mandalore. So by the time Din is taken in and he grows up in a post-Death Watch Tribe, members of the sect could have easily probably still numbered in the thousands.
So anyway. Where was I going with this? I don't know, I think I lost the plot somewhere, but by the time Mando era rolls around, Mandalorians who are affiliated with the Tribe/Children of the Watch are at their most insular, but perhaps are also constitute a good portion of the existing Mandalorian diaspora after the Purge in 4-5 ABY. And Din lived in a sizeable enough community as a foundling that he had no good reason to question their numbers or they represented the typical Mandalorian: insular, secretive, etc etc. He's seen how many members of the Tribe there were on Concordia, believes there were probably more hiding out elsewhere before the purge (whether that be on Mandalore itself or beyond), and now every 40-ish person unit has their own beroya making ends meet for them. So it would sort of make sense in his brain that he could just randomly ask around the Outer Rim to find out if anybody had seen people who look like him and eventually get a positive result. He wouldn't be shocked to finally meet Bo-Katan and her crew. But he absolutely WOULD be gobsmacked that these people who wear beskar'gam and call him brother would casually take off their helmets in front of him. Because that does not fit in his worldview at all.
Anyway. I'm done.
