The Maasai ruled the plains from Lake Turkana to the north and Lake Manyara to the north of Tanzania.
Their sphere of influence could be traced from Meru to the east, Kwale at the coast and Mumias to the west. They were driven by their passion for cattle and warfare. Warfare was meant to acquire and protect cattle as well as consolidate pasture. The Maasai terrorised their sedentary neighbours who practised agriculture like the Kikuyu, Kamba and Embu at will.
However, the relationship between Kikuyus and Maasai was peculiar, what would end up in today's slang as frienemies. The Kikuyu word for Maasai is 'ukabi', which is derived from the common pre-colonial name for Maasai 'Wakwabi' but also synonymous with Kikuyu word for 'enemy'.
This must have come from around Nyeri where Iloikop Maasai (Laikipiak) had a deep inclination to aggression and raids. On the other hand, when the Laikipiak were defeated by the Purko Maasai in an inter-clan feud around 1870 most of them fled to Kikuyu homes around Nyeri because they had relatives there.
Kikuyu and Maasai formed collaborations to raid their neighbours' cattle. Joint Maasai-Kikuyu raids against the Kamba were reported around 1895. There is also the legendary figure of Wangombe from Nyeri who sought Maasai mercenaries to help him raid the Ndia and later other Kikuyus in Mukurwe-ini area for cattle. Kikuyu clans had pacts with Maasai clans for protection.
There was also perpetual war marked by raids from both sides, which historians call "friendly matches" as they were conducted within strict rules. Bitterness crept in if one party went against the laid down rules of engagement. Their way of life was complimentary; the pastoralist Maasai needed agricultural produce while Kikuyus could do with some animal products. Through trade, other things also happened so much that several Kikuyu mbari (clans) claim that either their ancestors were Maasai or their clan has Maasai blood.
Pastoralists were vulnerable to famine and their cattle were susceptible to diseases like rinderpest. This was a constant threat to Maasai's source of livelihood, which made them move around a lot.
In such seasons they would seek refuge in their Kikuyu neighbours to avoid going far in search of food and pasture.
If there had been hostilities before such a season, Maasai sent emissaries to make peace with Kikuyus. Negotiations ensued and in the end, they would hold a religious ceremony where both parties took an oath to abide by the peace treaty called "munyoro" in Kikuyu.
Anyone who went against the treaty was visited by a natural calamity or handed over to the party he had infringed for punishment.
The Maasai gave their children and women to Kikuyus in exchange for food with the hope of paying a ransom during good times and taking them back. This practice was common among African communities in the past. Such children and women became full members of their adopted Kikuyu families until they were ransomed or fully integrated if they were left.