In history we see many examples where a conquered people ceased to speak their native language and began speaking the conqueror's language, and also many examples where conquering groups ceased to speak their original language and began speaking the native language. For a long time I've wondered what factors cause either of these options to occur when a territory is conquered, and did not yet find a satisfactory answer. Here are some examples for both cases, to provide grounds for discussion:
- When the Anglo-Saxons conquered England, the native population switched to speaking (old) English, rather than vulgar Latin (or Celtic languages).
- Native peoples all over Latin America switched to Spanish (or Portuguese) after the Spanish conquest. Note that this includes the Inca empire, which was solid and well-established at the time.
- Egyptians stopped speaking Coptic and switched to Arabic after the Arab conquest.
- Gauls in Iberia, France and England switched to speaking Latin after the Roman conquest.
- The English continued to speak English after the Norman conquest, and didn't switch to French; the Norman ruling elite eventually switched to English (of course this brought a lot of French influence into English, but nevertheless I'm puzzled by the fact that the language remained English).
- Many cultures along the eastern Mediterranean continued to speak Greek despite the Romans conquering them, which was an important factor in the Roman empire eventually splitting to east and west. (Compare to most of the western Mediterranean switching to Latin, as mentioned above)
- Iberia didn't switch to Arabic after the Arab conquest, but continued speaking Latin. Neither did Persia/Iran, which continues to speak Persian.
- France continued speaking Latin after the Frankish conquest; the Frankish ruling elite eventually abandoned their original Germanic language and switched to Latin. The same happened to the Lombards in Italy, where Latin continued to be the dominant language.
I'll be happy to hear explanations for these examples and other similar ones. Why were the Anglo-Saxons able to impose their language, for example, while the Franks and Lombards couldn't? What differentiates between Egypt, Iberia and Persia in terms of the adoption of Arabic? In general what factors decide or influence whether or not people adopt their conqueror's language, compared to the reverse situation?