What is "haestingas"

The Haestingas, or Heastingas or Hæstingas, were one of the tribes of Anglo-Saxon Britain. Not very much is known about them. They settled in what became East Sussex sometime before the end of the 8th century. A 12th-century source suggested that they were conquered by Offa of Mercia, in 771. They were also recorded in the Anglo-Saxon Chronicle (ASC) as being an autonomous grouping as late as the 11th century.