The Kerma culture or Kerma kingdom was an early civilization centered in Kerma, Sudan. It flourished from around 2500 BC to 1500 BC in ancient Nubia. The Kerma culture was based in the southern part of Nubia, or "Upper Nubia" (in parts of present-day northern and central Sudan), and later extended its reach northward into Lower Nubia and the border of Egypt. The polity seems to have been one of a number of Nile Valley states during the Middle Kingdom of Egypt. In the Kingdom of Kerma's latest phase, lasting from about 1700 to 1500 BC, it absorbed the Sudanese kingdom of Sai and became a sizable, populous empire rivaling Egypt. Around 1500 BC, it was absorbed into the New Kingdom of Egypt, but rebellions continued for centuries. By the eleventh century BC, the more-Egyptianized Kingdom of Kush emerged, possibly from Kerma, and regained the region's independence from Egypt. The primary site of Kerma that forms the heart of the Kingdom of Kerma includes both an extensive town and a cemetery consisting of large tumuli. The level of affluence at the site demonstrated the power of the Kingdom of Kerma, especially during the Second Intermediate Period when the Kermans threatened the southern borders of Egypt. Until recently, the Kerma civilisation was known only from the townsite and cemeteries of its metropolitan centre and smaller sites in Kerma, Sudan. However, recent survey and excavation work has identified many new sites south of Kerma, many located on channels of the Nile, now dry, which lay to the east of the modern course of the river. This pattern of settlement indicates a substantial population and for the first time provides us with some sort of context in which we can place Kerma itself. Survey work in advance of the Merowe Dam at the Fourth Cataract has confirmed the presence of Kerma sites at least as far upriver as the Abu Hamad/Mograt Island area. Kerma was evidently a sizable political entity - Egyptian records speak of its rich and populous agricultural regions. Unlike Egypt, Kerma seems to have been highly centralized.