Captain John Smith sailed up the Eastern Branch of the Potomac and was well received by the Nacotchtank, the Native Algonquin people in present-day Anacostia
. The Captain's oldest map, published in 1612, marks the area as Natcotchtank.
In 1621 the small sailing vessel, Tiger, headed up the Potomac from Jamestown, Virginia, with 26 men aboard. The goal of the trip was to trade corn with the Native Americans met by Captain Smith. The Nacotchtank ambushed the group and all the men were killed or taken prisoner. Henry Fleet was among those taken captive, and remained with the Natcochtank for five years, learning their language, customs and way of life.
After returning to Jamestown, Fleet made a few more journeys up the river to trade with his former captors. On one trip in 1632, he described in great detail his journey upriver. An entry of importance in the journal was the first referral to the location with the anglicized name of Nacostine, rather than Natcotchtank.
The next step in the etymology the name appears to be found in reports sent to Rome by the Jesuit fathers accompanying Leonard Calvert
, the first Proprietary Governor of the Colony of Maryland. These reports refer to the area and the natives as Nacostine and add the prefix "A" to becoming a more recognizable Anacostines or Anacostans.
John Smith's map below is pretty amazing. Click on it to get a blown up version of it.