What were the most powerful kingdoms to develop on mainland southeast asia by a. d. 1500?

The Khmer and Angkor empires. Hope this helped :)

the option which was not a function of missionaries in the northwest was the first one - they established posts for trading furs and other goods.

missionaries were sent around the world to spread religion and their knowledge and others - they were not merchants who sold furs and other goods.

sense of self-interest