Complex sentence: The cattle-killing frenzy affected not only the Gcaleka, Sarhili's clan, but the whole of the Xhosa nation; it is estimated that the Gcaleka killed between 300,000 and 400,000 head of cattle.
Split into simpler sentences: The cattle-killing frenzy affected not only the Gcaleka, Sarhili's clan, but the whole of the Xhosa nation. Historians estimate that the Gcaleka killed between 300,000 and 400,000 head of cattle.