At the time, this would have been a nicer place to visit:
[T]hey would have a found a land dominated not by desert, but by lakes, vegetation and wildlife.
Scientific studies published in the last few years show that there were two large lakes in the country. One of them, Lake Bodele, was a 91,000 square kilometre water body, making it larger than modern day Lake Superior. To the south there was Lake Chad, at that time a 22,000 square kilometre entity about the size of Lake Erie.
These bodies of water used to be even bigger, at one point they formed one large mega-lake. “At its peak sometime before 7000 years ago the lake was over 173 m deep with an area of at least 400 000 square kilometres, bigger than the Caspian Sea, the biggest lake on Earth today,” writes scientists Nick Drake and Charlie Bristow in a paper.
The journey to the West, which was the direction in which the afterlife was located in Egyptian mythology, included landmarks similar to those described in the land of the dead in Egyptian religious texts, although it isn't the only place to make that claim.
This expedition would have taken place about two thousand years after the domestication of African Sahel crops (which is a likely source of the expansion of the Niger-Congo languages and the population genetics of West Africa), which appeared around 4000 BC when the Sahara was at its wettest.
This expedition would also have taken place close in time to what some archaeology suggests could be the time that sheeps and goats were introduced to sub-Saharan Africa, an event that could plausible be associated with the arrival of the genetically distinct Chadic language speakers into the regions where they are found today, possibly close in time to the arrival of Ethiosemetic peoples into Ethiopia, probably also bringing sheep and goats with them.
I'll recall some observations I made earlier:
The Lake Chad basin is also home to two of the most notable genetic outlier populations in Africa: the Chadic language speakers of North Cameroon, who have a strong element of a Y-DNA haplotype (R1b) most similar to one found mostly in the North Atlantic and Northern Mediterranean, and Fulani language speakers of North Cameroon, who share a Y-DNA haplotype (T) with the Upper Nile basin, Somolia, the Balkans and a swath of Dravidian language speakers in Central and Eastern India. Lake Chad's fluctuations in extent are also believed to be central to the history of the Nilo-Saharan languages.
The Caspian Sea also has fairly little known but important climatalogical history that is important to recent human pre-history. The Caspian was connected to the Aral and Black Seas by water for some part of the period after the Last Glacial Maximum, and there is evidence that its highest and lowest surface levels have varied by 100 meters in relatively recent times. Rock art from around 4000 B.C. in the Caspian Sea depicts boats similar to those found in Egypt at around the same time. There is also evidence of giant stone monument construction there. There also appear to be connections between Caucusian geographical place names and names found in the Egyptian Book of the Dead.
It isn't clear to me if the references alluded to by those seeking a connnection between the Caspian Sea basin and the Book of the Dead, and the Lake Chad basin and the Book of the Dead, are the same passages. Both endorheic basins seem to hide some undiscovered parts of human history.
I'd previously suggested that these genetic outliers might simply have followed the White Nile to its source and then crossed the short divide into the Lake Chad basin but the discovery of a documented expedition around 4000 years ago and an awareness of the greater extent of the lakes in that basin at the time makes a more direct route seem plausible.