By the time that Plymouth Colony and the Massachusetts Bay colony were being established, the Pequots had established military dominance among Indian tribes in central and eastern Connecticut. They numbered some 16,000 in the most densely inhabited portion of southern New England. The smallpox epidemic of 1616–19 killed roughly 90-percent of the Indians on the eastern coast of New England, but it failed to reach the Pequot, Niantic and Narragansett tribes, and this assisted the Pequots in their rise to dominance. But the Massachusetts smallpox epidemic in 1633 devastated the region's Indian population, and historians estimate that the Pequots suffered the loss of 80-percent of their entire population. By the outbreak of the Pequot War in 1637, their numbers may have been reduced to about 3,000 in total.