From this thesis:
Following the Charter Act of 1813, which stipulated that the British administration must take more responsibility for the religious and moral improvement of the people of India (Chaube 1999: 53), William Carey of the Serampore mission sent his first convert, Krishna Chandra Pal, to work among the Khasis of Sylhet on the invitation of the British magistrate of Sylhet. Pal’s mission yielded seven converts, all of whom were encouraged by the enthusiastic magistrate to be baptised immediately before instruction. Other missionaries were also operating from the Assam side into the Naga Hills. F. W. Clark, another American Baptist Missionary, started his work from Assam in 1871 to penetrate the Ao Naga country.
158 Subsequently, due to the interest in missions providing a humanitarian resource for the administrators, primarily in the field of education, the American Baptist Foreign Mission Society (ABFMS) was invited from Burma. They set up their office in Manipur in 1894, after an initial attempt in 1836 failed due to opposition from the local government, who had made Vaishnavite Hinduism the main religion by a royal edict in 1705 (Dena 1988: 31). This was followed by an autonomous mission society called Arthington Aboriginese Mission Society (AAMS) funded by a wealthy millionaire, Robert Arthington from Leeds, United Kingdom. Its minister, Rev. Pettigrew, was the first official missionary to receive full patronage from a British official (Mr. A. Porteous, the Political Agent of Manipur) in the region. Arthington’s concept was based on the idea that ‘every tribe in every land shall have the Gospel’ (Dena 1988: 32). Pettigrew’s intention was to penetrate the largely Vaishnavite Manipuri population. But the Manipuri people saw his intentions as imperialistic and connected with the British government policy. Due to this setback, he shifted his focus to the hill inhabitants, primarily the Nagas and Kukis.