Background: The Mashantucket Pequot Tribal Nation is a federally recognized Native American nation in the state of Connecticut. They are descended from the Pequot people, an Algonquian-language tribe that dominated the southern New England coastal areas. Within their reservation in Ledyard, New London County, the Mashantucket Pequot own and operate Foxwoods Resort Casino. As of 2012, it is the world's largest resort casino in terms of gambling space and number of slot machines.
Context: Archeological and linguistic research has revealed that the recorded historic tribes encountered by the Europeans emerged at different periods and often undertook migrations. Various tribal oral histories also attest to major migrations of tribes and the emergence of new tribes over time. But such archeological studies have shown that the Pequot people and their ancestors had been in this region for thousands of years before European encounter. In the early years after European contact through trading with fishermen, the coastal tribes began to suffer high fatalities from new infectious diseases, to which they had no immunity. During the colonial years, Europeans recorded intertribal warfare, shifts in boundaries, and changes in power among the tribes. At one time some scholars believed that the Pequot migrated from the upper Hudson River Valley into central and eastern Connecticut around 1500. The theory of Pequot migration to the Connecticut River Valley can be traced to Rev. William Hubbard, a Puritan colonist. In 1677 he suggested that the Pequot had invaded the region some time before the establishment of Plymouth Colony. In the aftermath of King Philip's War, Hubbard wrote Narrative of the Troubles with the Indians in New-England, to explore the ferocity with which New England's Native peoples had attacked the English. He did not recognize that Connecticut and the Massachusetts Bay Colony had failed in their diplomatic efforts and promoted conflict through their encroachment on Native lands. Hubbard may have projected the colonists' status by classifying the Pequot as "foreigners" to the region. 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." The book was published in the mid-nineteenth century. Contemporary scholars have generally concluded that archaeological, linguistic, and documentary evidence all show the Pequot and their ancestors were indigenous for centuries in the Connecticut Valley before the arrival of Europeans. By the time the English colonies of Plymouth and Massachusetts Bay were being established, the Pequot had established dominance of the political, military, and economic spheres among Native Americans in what is now central and eastern Connecticut. Occupying the coastal area between the Niantic River of present-day Connecticut and the Wecapaug River in western Rhode Island, the Pequot numbered some 16,000 persons in the most densely inhabited portion of southern New England. CANNOTANSWER
Question: What have they done in the early ages?. Whats the answer?

the Pequot had established dominance of the political, military, and economic spheres among Native Americans