At about the same time, the Boers began to encroach upon Basotho territory. After the Cape Colony was ceded to Britain at the conclusion of the Napoleonic Wars, farmers who opted to leave the former Dutch colony were called the voortrekkers ("pioneers") and moved inland where they eventually established independent polities.

At the time of these developments, Moshoeshoe I gained control of the Basotho kingdoms of the southern highveld. Universally praised as a skilled diplomat and strategist, he moulded the disparate refugee groups escaping the Difaqane into a cohesive nation. His leadership allowed his small nation to survive the obstacles that destroyed other indigenous South African kingdoms during the 19th century, such as the Zulu hegemony, the inward expansion of the voortrekkers and the plans of imperial Britain.

In 1822, Moshoeshoe established the capital at Butha-Buthe, an easily defensible mountain in the northern Drakensberg mountain range, thus laying the foundations of the eventual Kingdom of Lesotho. His capital was later moved to Thaba Bosiu.

To deal with the encroaching voortrekker groups, Moshoeshoe encouraged French missionary activity in his kingdom. Missionaries sent by the Paris Evangelical Missionary Society provided the King with foreign affairs counsel and helped to facilitate the purchase of modern weapons.

Aside from acting as state ministers, missionaries (primarily Casalis and Arbousset) played a vital role in delineating Sesotho orthography and printing Sesotho language materials between 1837 and 1855. The first Sesotho translation of the Bible appeared in 1878.

In 1868, after losing the western lowlands to the Boers during the Free State–Basotho Wars, Moshoeshoe successfully appealed to Queen Victoria to proclaim Lesotho (then known as Basutoland) a protectorate of Britain. Accordingly, the British administration was established in Maseru, the site of Lesotho's current capital. Local chieftains retained power over internal affairs, while Britain was responsible for foreign affairs and the defense of the protectorate.

In 1869, the British sponsored a process to demarcate the borders of Basutoland. While many clans had territory within Basutoland, large numbers of Sesotho speakers resided in areas allocated to the Orange Free State, the sovereign voortrekker republic that bordered the Basotho kingdom.

The Sotho language, seSotho, is a Bantu language closely related to seTswana. Sotho utilizes click consonants in some words, while sePedi and seTswana do not have clicks. Sotho is spoken in the Kingdom of Lesotho and in South Africa. It is concentrated in the Free State, Gauteng and Eastern Cape Provinces, with small groups of speakers in Namibia and Zambia.

Sotho is 1 of the 11 official languages recognized by the South African Constitution and 7.9% of the South African population uses it as their home language. It is a tonal language governed by the noun, which is split into various classes. It is known as an agglutinating language (a combination of simple word elements to express a specific meaning), with many suffixes and prefixes used in sentence construction causing sound changes.

It is rich in proverbs, idioms, and special forms of address reserved for elders and in-laws. Currently, Sotho has two spelling systems, one in use in Lesotho and another in South Africa. For example, in Lesotho a common greeting is Khotso, le phela joang? (literally, "Peace, how are you?"). In South Africa, the word joang (how) is written jwang, and khotso is written kgotso.

Sotho was one of the first African languages to become a written language and therefore Sotho literature is extensive. South Sotho is comprised of the Fokeng, Tlokwa, Kwena, Phetla, Phuti, and Pulana dialects or varieties and according to scholars the written form was originally based on the Tlokwa dialect. Today the written language is mostly based on the Kwena and Fokeng dialects, although there are variations. Sesotho was transmuted into writing by the missionaries Casalis and Arbousset of the Paris Evangelical Mission who arrived at Thaba Bosiu in 1833. One of the first novels in a South African language was Chaka, written in Sotho by Thomas Mofolo in the early years of the twentieth century. It is still read today and has been translated into a number of languages.

(source used 101lasttribes.com but please if you have nothing to do research this tribe)