What is "modderpoort"

Modderpoort, also known as Lekhalong la Bo Tau or ‘The Pass of the Lions’, is the site in the eastern Free State, South Africa, where the Anglican Missionary Brotherhood, the Brotherhood of St Augustine of Hippo, was established by Bishop Edward Twells in the late 1860s. It is also associated with the BaSotho prophetess Mantsopa, while the ‘sacred landscape’ in the vicinity includes San rock painting sites.