Which Christian African Empire is also influenced by Judaism and Islam through trade?

Kingdom of Aksum.

Explanation:

The kingdom of Aksum was located in the area of the present-day highlands of Eritrea and northern Ethiopia, on the shores of the Red Sea, roughly in the first millennium of our era. It was born in the first century and disintegrated around the 9th century. The center of the kingdom was the city of Aksum.

Aksum traded with India and the eastern Mediterranean. Ivory, tortoiseshell, hooves, spices, incense, gold, gems and slaves, among others, passed through Africa. In return, metals, glass, textiles, wine and olive oil were received. The power of the kingdom peaked in the time of King Ezana in the 300s, when the state converted to Christianity. It extended to the Red Sea and also covered most of present-day Yemen.

the answer to your question is a. the salt plains

in 1811, he led an expedition, known as the george c. sibley expedition, to improve relations with the pawnee and kansa tribes, and also to locate the rumored jefferson's salt mountain