The descendants of Bugis mercenary forces that liberated Riau from east Sumatran invaders became an integral part of the local Malay community by the mid-nineteenth century. At that time Raja Ali Haji and Haji Ibrahim, two Malay authors of Bugis descent, wrote various tracts to legitimise their presence in Riau and to facilitate Bugis integration into the Malay community, but may have led to continuing divisions along ethnic lines in later years.