During the colonial years, colonists recorded inter-tribal warfare, shifts in boundaries, and changes in power among the tribes. Scholars believe that the Pequots migrated from the upper Hudson River Valley into central and eastern Connecticut around 1500. William Hubbard wrote "Narrative of the Troubles with the Indians in New-England" in 1667 to explore the ferocity with which the Pequot tribe had attacked the colonists. He described them as invaders from "the interior of the continent" who "by force seized upon one of the places near the sea, and became a Terror to all their Neighbors." Contemporary scholars suggest that archaeological, linguistic, and documentary evidence show that the Pequots were indigenous for centuries in the Connecticut Valley before the arrival of settlers.