Anga referred to a region in what is now Bihar, Jharkhand, West Bengal states of India, and Lipi meant script.  Anga Script is mentioned in an ancient Sanskrit language Buddhist book "Lalitvistar" (ललितविस्तर), which says Anga Lipi was one of the most important scripts among 64 other scripts of that time. The script was specific to the Anga region, or Anga Mahajanapada, and was among those known to Buddha. The script was mentioned as the fourth most important script of Ancient India, and was used to write Anga Desh-Apbhramsa or Aangi, now Angika, around 600 BC. Some of the sixty four scripts mentioned in "Lalitvistar" were mythical, but some, including Dravid, Anga and Banga, were real.
Anga Lipi and Banga Lipi might have been derived from Brahmic, with some regional characteristics. This supports the belief that the development of local characteristics in alphabets, was continuing from earlier times.
It reflects the early development of local variants of Indian alphabets.