They were nilotes - who assimilated mostly male oromos/gallas. Sort of rejected cushites married nilotic women - and formed a tribe - then followed cushites down south - and later in east africa when Maasai arrived seperated.
Kalenjin, somalis and oromos have stayed in east africa longest after aboriginal. Its why you see all of them being good althetes - because of their thousands of years adapation in rift valley
Before iron tools by bantus...they used stone tools...
So who were the proto kalenjin?