The African Desert

525 BCE:
During the time of Buddha in India and few decades after Babylonians sacked Jerusalem, Cambyses II was the King of Persia. Before that he was a video game. Heh! In 525 BCE, Cambyses II sent an army of 50,000 warriors from Thebes to attack the Siwa Oasis near the Libyan border. The army walked for seven days in the Egyptian desert and reached an oasis. Once they left, no one heard from them again.

Now, two top Italian archaeologists claim to have found striking evidence that the Persian army was indeed swallowed in a sandstorm. Twin brothers Angelo and Alfredo Castiglioni are already famous for their discovery 20 years ago of the ancient Egyptian “city of gold” Berenike Panchrysos. Right there, the metal detector of Egyptian geologist Aly Barakat of Cairo University located relics of ancient warfare: a bronze dagger and several arrow tips.
“We are talking of small items, but they are extremely important as they are the first Achaemenid objects, thus dating to Cambyses’ time, which have emerged from the desert sands in a location quite close to Siwa,” Castiglioni said.[Vanished Persian Army Said Found in Desert]

120,000 and 45,000 years ago:
If the desert was so dangerous, then how did the human ancestor walk out of Africa crossing the Sahara?

Wet spells in the Sahara may have opened the door for early human migration. According to new evidence, water-dependent trees and shrubs grew there between 120,000 and 45,000 years ago. This suggests that changes in the weather helped early humans cross the desert on their way out of Africa.
While about 40 per cent of hydrocarbons in today’s dust come from water-dependent plants, this rose to 60 per cent, first between 120,000 and 110,000 ago and again from 50,000 to 45,000 years ago. So the region seemed to be in the grip of unusually wet spells at the time.
That may have been enough to allow sub-Saharan Stone Age Homo sapiens to migrate north: the first fossils of modern humans outside Africa date from 93,000 year ago in Israel. And both genetic analysis and archaeology show that humans didn’t spread extensively beyond Africa until 50,000 years ago, suggesting a second migration at the time of the second wet spell.[Stone Age humans crossed Sahara in the rain]

14th century CE:
Once Mansa Musa, the tenth emperor of the Mali empire, visited Mamluk Egypt on the way to Mecca. Mali was such a rich empire at that time that Musa is depicted holding a golden nugget and wearing a golden crown. His visit to Egypt with so much gold caused an inflation that lasted a decade.
While Mali had gold, they did not have salt. So during that period, traders used to cross the Sahara carrying salt slabs with them to Mali. In return they would get gold. This sub-Saharan trade happened due to the domestication of one animal: the camel.
Few million years into the future:
Volcanic processes are working beneath the Ethiopian desert which are identical to those under the bottom of the oceans. Geologists think it is the beginning of a new ocean.

In 2005, the earth cracked open in Ethiopia. Two volcanic eruptions shook the desert, and a 35-mile-long rift opened in the land, measuring 20 feet wide in some places. Now a new study adds weight to the argument that the opening of this crack marks the first step in the formation of a new sea that may eventually separate East Africa from the rest of the continent. Says lead researcher Atalay Ayele: “The ocean’s formation is happening slowly, likely to take a few million years. It will stretch from the Afar depression (straddling Ethiopia, Eritrea and Djibouti) down to Mozambique”

Notes:

1. Supreme Council of Antiquities of Egypt has a note which says that news of the discovery of the army of Cambyses are “unfounded and misleading.”
2. Rogueclassicism: Cambyses’ Lost Army Found? Don’t Eat That Elmer …
3. The Musa story comes from the MMW4 lecture on Africa