"Europeans" isn't the answer i'm looking for. I was always told it was at the Berlin Conference, but following the text of the contract, it only states that as soon as one of the co-contractors control a certain coastal area it mustn't be infringed upon, so it was divided on a first-come-first-served basis. I didn't find anything in that contract about the infamous straight edge that made the border between Chad and Libya, for example.
While I cannot explain a lot of the borders I do know a little about the Kenya - Tanzania border.
It is commonly believed that Queen Victoria gave her grandson, Kaiser Wilhelm, Mt. Kilimajaro for his birthday, this is untrue. Instead an arbitrary line was drawn separating Kenya and Tanzania down to the coast. It was mostly straight but curved around Mt. Kilimajaro.
In essence there is no grand story around this border. Just that Mt. Kilmajaro is the reason it changes where it does. Here is a map in case you are interested.
Source:
Philip Briggs : Guide to Tanzania
David Else : Trekking in East Africa
