Slightly more woodland cover in East Africa. Pollen in Lake Victoria around 5,000 years ago seems to indicate a greater-than-present tree cover relative to grass cover, which may be due to a moister climate or perhaps weaker human influence. The general view of slightly moister-than-present conditions with more woodland is corroborated by other workers, such as Maitima (1991) who finds that in the lowlands of the central rift valley there was a drying after 6,500 years ago, with loss of woody vegetation and replacement by grasslands, but only giving the mainly grassland vegetation similar to today's by around 4,000 years ago. In east Africa, lake level evidence generally seems to suggest moister-than-present climates in the Ethiopean rift region and the Ethiopean Plateau, but relatively similar-to-present conditions in the region of the western rift and Lake Victoria (Hamilton 1982) although many lakes do still seem to have slightly higher than today at around 5,000 years ago (Hamilton 1982).
http://www.esd.ornl.gov/projects/qen/new_africa.html