The Western Abyss
Point of divergence: in around 1300 AD, there's an earthquake that blocks off the strait of Gibraltar. (Okay, this is a bit ASB, but still).
No longer having any water flowing in from the Atlantic, the Mediterranean slowly starts to dry up...
Fastforward seven hundred years, and here's where you end up.
Europe, in the year 2000.
Major Powers of Europe
10) The Caliphate of Rum (a.k.a. Turkey). United the Turkish tribes of Anatolia, and went on to take over the Balkans and the Italian peninsula as the sea slowly dried up. Despite its location, Rum is a very different beast to what one would expect in this region IOTL, for it is a much drier and less densely populated area. No longer a main trade hub, Rum is more akin to Central Asia in climate now, where the Turks' ancestors had come from. The deep lakes of the former Mediterranean basin can only even be visited in the winters, for in summers it is too warm for human habitation. The population is predominantly Sunni Muslim and Turkish-speaking- while its people are descended from a variety of places, such as the Greeks and Italians, Arabs from North Africa who had migrated north as their homelands dried up, and others moving throughout the Caliphate, they generally all ended up assimilating into the Turkish populace.
11) The Roman Empire. The strongest European Christian power to remain in existence, the Roman Empire received a lot of immigrants from the Mediterranean region (predominantly Italy) as the lands there dried up. The Italians and Slavs from the south easily settled into German lands which had been depopulated by the Black Death of the 1350s. Has been the subject of multiple attempts at conquest by Rum to the south; it's slowly progressing technologically, but nothing like Europe's progress IOTL.
18) The Wu Dynasty (or Western Wu). An Chinese dynasty which had briefly stretched all the way from the Pearl River to the Volga in the 1700s, it soon fell apart due to its large size, but by that point the Volga River region had had enough Chinese settlers that the Wu Emperor fled from Nanjing to Sarai as he saw his empire disintegrating. Slowly reviving itself and strengthening, the Wu now have a Baltic port and are demonstrating their power more and more. An interesting hybrid culture has developed here, as the Chinese settlers of the Volga (or
A-de Shui) interact with Slavs, Tatars, etc, and the culture is increasingly different to that of China proper.
Medium Powers
5) The Kingdom of France. Having lost its south to Aragonese jihadis, and increasingly irrelevant in comparison to the Roman Empire, France is sliding down towards minor power status.
6) The Kingdom of Aragon. Now has a Muslim king, but its population is still mostly Christian. It's a bridge between the Christian and Muslim worlds.
8) The Kingdom of Spain. Castile and Portugal united; it's now locked in an endless sort-of cold war with Cordoba, back and forth and back and forth...
9) The Caliphate of Cordoba. The city of Cordoba was recaptured in the 1300s by the Marinid sultan, who subsequently claimed the title of Caliph; the lands of al-Andalus were repopulated by Arabs and Berbers of North Africa who found their homelands increasingly uninhabitable.
15) The Kingdom of Prussia. Descended from the Teutonic order.
17) The Kingdom of Poland. Sandwiched between three great powers, trade passes through Poland a lot.
19) The Kazakh Horde. Central Asia keeps shifting hands between various different states following the Wu's loss of control of the region.
21) The Armenian Empire. Founded by a Muslim Armenian emperor, it has successfully challenged the Turks' dominance of the region.
22) The Sultanate of Egypt. It's not very powerful, but at least it controls the holy cities.
23) The Persian Empire. Cycles between various dynasties, but has steadily remained fairly powerful.
Minor Powers
1. Iceland; 2. Ireland; 3. Scotland; 4. England; 7. Navarre; 12. Denmark; 13. Sweden; 14. Finland; 16. Russia; 20. Georgia.
As of 2000, the evaporation of the Mediterranean is finally complete, but as the world enters its third millennium, change is on the horizon. Malian explorers have reported discovering an new continent to the West, although in fact it had been discovered on the other side by the Japanese hundreds of years prior, and the island of Hokkaido (Vancouver Island IOTL) is fairly well-settled by the Japanese.
In Egypt, the Sultan is raising the question of whether it would be at all viable to cut a canal from the Red Sea through Suez, in order to refill the Mediterranean Sea... such a policy would be unpopular, but this Sultan is rather eccentric and seems to be very interested in the idea...
And in a striking contrast to Europe's stagnation in technological progress, on the Indian subcontinent an Industrial Revolution is brewing...
One thing is for certain, the next millennium will look very different to the last.