A group of Kirinyaga elders have moved to court seeking to have Kirinyaga people(Akirinyaga) recognized as Kenya's 45th tribe and not Kikuyus.

Fair enough, I say. I always wondered why when discussing who Kikuyus are and their original homelands, we only hear of Murang'a, Nyeri & Kiambu.

Most Kikuyus seem to have originated from Muranga and Nyeri before spreading to other areas possibly because of family disagreements.
Kiambu people were mainly from Muranga while Nyandarua and Kiarinyaga have their roots in Nyeri.

Akirinyaga are more Meru than Kikuyu. Their language and Kimeru has so many commonalities. Infact they just speak directly to each other without a need for any translation

I agree the true kikuyu are the kirinyaga people. I am from kiambuu and all folklore suggests that. I am now wandering how can the true agikuyu abandon their name.what will they call themselves? Kirinyaga is a place. I think no tribe in Kenya is named from a place but rather a particular area is named for or by the people inhabiting that area.

There is nothing like Kirinyaga tribe. They are just Agikuyu with Akamba accent. The vocabulary is the same but pronunciation is different. Even Embu's should be classified as Agikuyu.

My take: Akirinyaga are a product of isolation from other Agikuyu. When one group becomes isolated, their language starts to evolve into a different language.

How similar two languages are depends on how long the two were isolated or split. From that perspective, AMeru people split from Agikuyu much longer ago than Embu people who in turn split from Agikuyu much longer ago than Akirinyaga.

It is true that had the British not come and if societies remained as they were in the 1800s then , most Kenyan ethnic groups would have splintered into much smaller groups. Some Maasais would have spread as far East as Voi and would now be a different ethnic group. Abaluhya would have split into 28 sub groups and Maragolis and Bukusu would no longer be considered Luhyas because their langaues would have evolved further apart. Some Luo groups would have migrated as far south as Mozambique or Lake Tanganyika and would now be speaking a different language with plenty of influence from Kisukuma. Mijikenda would be Miji kumi na Kenda. And Digo would no longer be part of them

Some of this is hyperbole. But its the general progression of languages. Historically, languages evolve constantly when isolated from the parent language.

interesting discussion... where did the Kikuyu originally come from? since the Kamba, Kikuyu, Meru, Embu and Akirinyaga once had a common heritage - what was the name of these people? the proto"Central" people.

Thagicu?

Are you aware that many who regard themselves as Agikuyu are actually Dorobos?

There are Bantus in Cameroon which seems to lie more to the North than Kenya.