Answer by taking a quote from the following article:

The Powhatan People (sometimes Powhatans) (also spelled Powatan) are an Indigenous group traditionally from Virginia. In some instances, The Powhatan, may refer to one of the leaders of the people. This is most commonly the case in historical writings by the English. The Powhatans have also been known as Virginia Algonquians, as the Powhatan language is an eastern-Algonquian language also known as Virginia Algonquian.

The capital village of "Powhatan" was believed to be in the present-day Powhatan Hill section of the eastern part of Richmond, Virginia, or perhaps nearby in a location which became part of Tree Hill Farm.  Another major center of the confederacy about 75 miles (121 km) to the east was called Werowocomoco. It was located near the north bank of the York River in present-day Gloucester County.  Werowocomoco was described by the English colonists as only 15 miles (24 km) as the crow flies from Jamestown, but also described as 25 miles (40 km) downstream from present-day West Point, measurements which conflict with each other. In 2003 archaeologists initiated excavations at a site in Gloucester County that have revealed an extensive indigenous settlement from about 1200 (the late Woodland period) through the early Contact period. Work since then has added to their belief that this is the location of Werowocomoco. The site is on a farm bordering on Purtain Bay of the York River, about 12 nautical miles (22 km) from Jamestown. The more than 50 acres (200,000 m2) residential settlement extends up to 1,000 feet (300 m) back from the river. In 2004, researchers excavated two curving ditches of 200 feet (60 m) at the far edge, which were constructed about 1400 CE. In addition to extensive artifacts from hundreds of years of indigenous settlement, researchers have found a variety of trade goods related to the brief interaction of Native Americans and English in the early years of Jamestown.  Around 1609, Wahunsunacock shifted his capital from Werowocomoco to Orapakes, located in a swamp at the head of the Chickahominy River, near the modern-day interchange of Interstate 64 and Interstate 295. Sometime between 1611 and 1614, he moved further north to Matchut, in present-day King William County on the north bank of the Pamunkey River, not far from where his brother Opechancanough ruled one of the member tribes at Youghtanund.

why did he move further north?
not far from where his brother Opechancanough ruled one of the member tribes at Youghtanund.