Meroe and Aksum

Aksum obelisk
These kingdoms south of Egypt traded with Egypt from early in the Bronze Age. Egypt was more powerful in war, but the people of Meroe and Aksum had things that the Egyptians needed, and so there was always a lot of trade between the two regions.
As early as 3000 BC, there was already trade from Nubia, south of Egypt, all along the Nile river to the Mediterranean Sea. The Nubians sold gold to the Egyptians, and also slaves, ivory, furs, and exotic live animals like elephants and lions. Nubians also sold diorite, a hard black stone, and granite, for Egyptian statues, and jewelry stones like carnelian and agate. In return, the Nubians bought Egyptian cotton and linen, glass, jewelry, perfume, and wine. Nubians also often used their profits to hire Egyptian architects and engineers, accountants and priests, to work on Nubian projects.
By the New Kingdom period in Egypt, about 1600 BC, there were also wars between Nubia and Egypt. The Egyptian pharaoh Tutmosis I invaded Nubia, and took over the kingdom of Kush as far as the fifth cataract of the Nile in 1580 BC. Egypt pretty much dominated Nubia for the next five hundred years or so, and what was left of Nubian power moved further south, to the kingdom of Meroe.
But after the collapse of the New Kingdom - about 1000 BC - the Kushite kingdom began to get stronger again, and by 748 BC, the Kushites attacked and conquered Egypt (as the 25th Dynasty).
After 150 years, in 591 BC, the Egyptians under Pharaoh Psammeticus II were able to throw out the Kushites and reconquer Nubia.When Egypt came under Persian control about 500 BC, Kush and Meroe also came under Persian influence. By 350 BC, however, Meroe was declining. This is probably because there was more and more trade by way of the Red Sea. Meroe, along the Nile, did not benefit from this, but the neighboring kingdom of Aksum did.
After the Romans conquered Egypt in 30 BC, the Kushites tried invading Egypt again, but the Roman army sent a force in 24 BC and they ended up signing a peace treaty. The Romans from then on traded along the Red Sea directly with Kush and Aksum, instead of always going through Egypt. Generally power in Nubia moved further south, and along the Red Sea rather than the Nile.
Starting in the 300's AD, the people of Nubia converted to Christianity, following the lead of the Egyptians and the Roman traders. Around the same time, the introduction of the waterwheel for irrigation helped Nubia produce much more wheat, barley, and millet than before, as well as wine grapes and dates.
Later history of Aksum and Meroe
To find out more about ancient Nubia, check out these books at Amazon.com or find them at your library:

The Ancient African Kingdom of Kush (Cultures of the Past) by Pamela F. Service (1998)
A Place in the Sun, by Jill Rubalcaba (1998)
The Nubians: People of the Ancient Nile, by Bob Bianchi (1994)
Daily Life of the Nubians, by Bob Bianchi (2004)
