Kalanga and Karanga are not tribes. If we are to be puritanical both names refer to a religion that was called the Mwari Cult by Europeans, before they later decided to steal the name Mwari and apply it to their god Jehovah (or Yahweh to use the original Hebrew transcription).
Makaranga or Makalanga (just like the names Christian and Muslim) encompass many groups of different ethnic origins that adopted the culture and way of life.
1. Who instigated the first Chimurenga? According to the history you were taught in school it was a Matabele High Priest or the Mlimo of Matopos who sent an emissary to Mashonaland. The British are at a loss as to why the Matebele would send an emissary to the Shona and most books either skirt around the subject or openly admit that they can't explain. The books also do not talk about what happened to the 'Mlimo'.
The Mlimo was assassinated by Frederick Burnham and Bonar Armstrong when he was leading a ceremony at Matopos. That is what brought a quick end to the war in Matabeleland.
The more important question is who was he? According to writings from the time, he was "High Priest of the Mwari, chief rainmaker (Wosana) of the tribe Makalanka." What this means is that he was not a Ndebele as we are taught in our schools but a 'Makalanka'.
If you listen to Kalanga folklore it gives very high prominence to Tjibelo and Tjibundula as important ancestral families of the Kalanga. Now ask yourself where did the emissary send by the Mwari priest go. He went to Mashayamombe and the surrounding people. Where was the Mashayamombe located and what is the area called today? Chivero. Where is Chivero if I may ask you?
Now go back to 1896 and try to find an explanation for why the Mlimo, who was recorded as a Makalanka at the time, would send an emissary to Chivero area. Does the relationship need to be more obvious? Or by the way, to explain Tjibundula let let me just draw your attention to Paul Matavire's song "KwaChiwundura vakandisungaaa!"
You may be asking yourself how come the people of Matopos are called Kalanga while those of Chivero are Karanga. (For now I don't have the time and space to tackle the misrepresentation that Karanga are only from Masvingo. Karanga are found as far afield as Mozambique's Uteve, Barwe and Tavara people. "Rove ngoma muTavara wee!". And possibly Zambia's Lozi people)
2. To answer your curiosity let me introduce you to the topic of transcription, how to represent spoken sounds in written form. When European missionaries came, they grappled with the problem of how to translate the bible into local languages. Local languages did not have a written form.
At first, different missionaries came up with different approaches. A mission station would try and come up with a written form for the language spoken around its location. However given dialectical differences even among mutually intelligible peoples, this resulted in many different transcription systems. An example of a local writing system now defunct is the original Kalanga which used Tj for the Ch sound in Shona or Tsh in Ndebele. This writing system survived in place names which is why many maps had the name Tjolotjo for Tsholotsho.
Even when writing accounts in English or other European language, explorers and missionaries often struggled with how to render given names of places and people. Thus you may find Nengomasha (who was an army general for Munhumutapa Gatsi Rusere) written as Ningomaxa or Ninkomaxa by different authors.
This happened with tribal names as well. Makalanka, Makalanga, Makaranga, Makalaka.
The many transcription systems made printing the bible, especially in those times when letters for lithography presses had to be carefully handcrafted, a very expensive exercise.
Eventually, missionaries started exploring ways to make printing the bible cheaper. To this end, in 1929 they hired a professor of Bantu Languages from the University of the Witwatersrand, Clement Martyn Doke. He spend a year interviewing natives in Southern Rhodesia before he came up with a recommendation.
The missionaries held a conference at Dadaya where Doke presented his recommendations among them a recommendation for Unified Shona. There was some debate on what name to call the language before Shona was agreed upon. From that point on the name Shona was used by missionaries in Southern Rhodesia.
On the other hand, the South African government did not quite agree with Doke's findings, and they used the name ChiKaranga, which they stopped using around 1955.
Going back to 1930 the missionaries agreed that to make printing the bible as cheap as possible, the country would be divided into only two regions along administrative lines used by the Southern Rhodesian government.
Everyone inside Matebeleland province would be taught to read and write Ndebele using the Nguni alphabet, imported from South Africa. Thus the Venda, Tonga, Kalanga, Nambya, etc were all now forced to learn Ndebele even though they didn't natively speak it.
Everyone else (Victoria, Manicaland, Midlands, and Mashonaland provinces) would be taught to read and write in the new Unified Shona that Clement Doke had recommended. The Shangani were thus forced to learn Shona.
As for Unified Shona itself, it was mainly based on Zezuru, Kaanga, and some Manyika. Why? The main missions driving the process, St Ignatius Chishawasha, Domboshawa, and Waddilove were in Zezuru speaking areas, Mogenster and Dadaya were in Karanga speaking areas, St Augstines Tsambe and Mt Selinda were in Manyika and Ndau areas.
I use the name Karanga with reservation. It was not the name used by missionaries for the dialect. Rather they called several related dialects from Victoria Province the Victoria Circle dialects. It is from this where the name ChiVhitori comes from.
The name Karanga itself was considered for the unified dialect but, after some debate, was discarded in favour of Shona. Some entities continued to use it though, which is why you find some of the earliest Shona textbooks may have titles like Chikaranga Chamandiriri.
Now for the last part. As you know the Nguni alphabet does not have R, while the newly proposed Shona alphabet did not have L (despite the R in Chikorekore sounding close to L).
Thus speakers of the same language were taught two different ways of writing the same or similar words. Those in Matabeleland were taught to write Kalanga while those in the rest of the country were taught to write Karanga. To be more accurate, they were simply taught they were Shona with the name Karanga returning to popular use after independence. Even it was used as a replacement for ChiVhitori which is totally incorrect. It should have been used as a replacement for the name Shona itself.
Now add to this mix some Europeans who could not properly pronounce local names, or who did not know how to render local names they found already written. Being British, these Europeans used British pronunciation for letter combinations. Thus the NG in Kalanga became soft like the English letter combination NG. (instead of being pronounced with a hard sound like in "blank" it was pronounced with a soft sound like in "belonging"). Victims of British mispronunciation even include country names Botswana and Uganda. Not to mention the district Buhera (which is why Uhera has become Bhowera?).
That in a nutshell Cde explains the main source of the difference between the names Kalanga and Karanga.
Most of those taught in Shona, except the Shangani, were fortunate that their native dialects were very close to the Unified Shona thus they could still speak them while writing in the new alphabet. Most of the differences are tonal.
For those in Matabeleland, it was a different story. They were essentially forced to abandon their native languages for the vastly different Ndebele.
Given that the people running the system were racist supremacists, they attached the social narrative that everyone had to speak Ndebele because it was the 'superior' language. They did not elevate to the same level as theirs though. When this narrative filtered down to the villages, it was often presented along the lines that if you were Nguni you were superior to those around you.
This is one of the reasons you find that people from Matabeleland are almost insanely fixated with being Nguni.
For the rest of us, it means nothing, if you are a muBarwe you are a muBarwe, and if the next man is a muHera so what? But in Matabeleland, it's a different story. Everyone wants to be Nguni. This was done to entice people away from their native languages under the perception that if you speak Ndebele you get closer to being Nguni.
Remember the main narrative which affects everyone including the Shona to this day, was that if you spoke English and adopted English mannerisms and culture you became superior to the rest of the natives. That is why kutaura Chirungu, especially with near-perfect accent, is considered a social construct of sophistication by the mentally colonized.
But I digress. Kalanga and Karanga are exactly the same thing (keeping in mind that there are many different marudzi in both groups). The divergence was caused firstly by different alphabets and then by different colonial socialization of communities
