In the sixth century BC, most of what we now know as Myanmar, Thailand, Laos, and Cambodia was sparsely populated. While migrants from the east coast of India had formed trading colonies along the coast of the Gulf of Martaban, these coastal areas of Myanmar and Thailand were also home to the Mon. By this time, the Khmer probably controlled Laos, Cambodia, and northern Thailand, while Upper Myanmar may already have been occupied to some extent by Myanmar tribes.