Studies of deaf children who are not exposed to a formal sign language indicate that the children spontaneously produce their own signs, called home signs, which emerge in development at the times of typical language milestones. however, the children relying on home signs are limited in that

I believe the answer is: they do not advance beyond the telegraphic phase of language

During the telegraphic phase of language, we would learn to differentiate longer and shorter words in order to determine which one is more efficient in the current context. Deaf people tend to unable to pass this since they never heard how long and short sentence sounds like.

the aksumite empire was an ancient kingdom located in what is now northern ethiopia from the period of 100 ad to 940 ad. its capital was the city of aksum. the kingdom established itself as one of the 4 great powers at its time, along with persia, rome, and china.

the kingdom was rich in goods like gold, iron, and salt. it established strong commercial ties with the regions governed by rome, egypt, and persia (arabia). aksum was a key location in this commercial network. trade was also facilitated with the introduction of the aksumite currency.

uhh idk for sure but i think it makes it difficult to pump the oil through the oil rigs