Uesugi, Akinori, (2018). "An Overview on the Iron Age in South Asia", in Abstracts for the International Symposium on the Iron Age in South Asia, 2 and 3 June 2018, at Kansai University, Osaka, p. 6: "...During the early second millennium BCE, the Bara-OCP (Ochre-Coloured pottery) cultural complex expanded from the Ghaggar valley to the western part of the Ganga valley. This cultural complex [...] has its origin rooted in the Indus Civilization in the preceding period, its eastward expansion indicates the colonization of the western Ganga valley probably giving great impetus to the Neolithic-Chalcolithic communities in the Ganga valley to transform into a more complex society..."
