Thaba Bosiu is a constituency and sandstone plateau with an area of approximately 2 km2 (0.77 sq mi) and a height of 1,804 meters above sea level.

Thaba Bosiu was used as a hideout by Moshoeshoe I and his subjects after they migrated from Butha-Buthe in 1824 escaping the ravages of the Difaqane/Mfecane Wars.

The plateau's large area meant it could hold enough livestock and provisions to support the people during a lengthy siege.

It is approximately 24 km east of the junction of the Caledon River that divides Lesotho from Free State.

[8] Mzilikazi attempted to attack Moshoeshoe I at Thaba Bosiu, trying to gather strength after escaping Shaka Zulu's rule; but was unsuccessful in his conquest.

[9] European invaders in 1852 and the Boers of the Orange Free State were unable to storm Moshoeshoe's mountain during the siege of Thaba Bosiu on 18 August 1865.

The siege of Thaba Bosiu continued until January 1866 when General Jan Fick and his men returned to Free State to reorganise.

At the time, Basotho faced large scale starvation and thus Moshoeshoe and his subjects agreed to the Orange Free State's terms.

This left Basotho with a significantly reduced cultivable area close to Thaba Bosiu, as well as 32 km of arable soil on the east bank of the Caledon River.

This was a reaction to Prime Minister Chief Leabua Jonathan’s governance (leader of the Basotho National Party - BNP).

A conflict between the security forces and demonstrators ensued, resulting in 10 dead and arrests of many opposition party leaders.

In 1957, Lekhotla la Bafo held a joint meeting with the Basotoland Congress Party (BCP) at Thaba Bosiu.