Nice Island, I'll Take It!

In 818, Emir Al-Hakam I of Cordoba faced a revolt from al-Ribad, one of the large suburbs of the city (at the time, Cordoba was one of the biggest cities in the world, having nearly half a million people).  The people were upset by Hakam's harsh tax policies, which he had enacted after the last revolt in 805, hoping to keep the people poor and helpless.

Unfortunately for the rebels, their attempt to storm the palace was easily defeated, and many of the mob were slaughtered in the streets.  After torturing and executing the ringleaders, Hakam took the extreme measure of rounding up and exiling every resident of al-Ribad, about 60,000 people.  Hakam was not one to put up with that kind of shit, apparently.  Most of the exiles moved to Morocco, but a large number, perhaps as many as 10,000, took up Mediterranean piracy.

Led by Abu Hafs, this pirate band, along with their families and their former neighbors, invaded and occupied the Egyptian city of Alexandria, intending to make it their new home.  The rulers of Egypt, of course, were not on board with this plan.  You can't just sail up to one of the most famous and important cities in the world and declare yourselves the new owners.

The Egyptians quickly marshaled their forces and besieged the city, reclaiming it about a year later.  So, the Cordobans set out again looking for a new home, and arrived at the island of Crete, then part of the Byzantine Empire.  After defeating the local garrisons, they set up shop on the island, and built the fortress of Chandax as their new capital.

Although the Byzantines sent several military expeditions to reclaim the island, the Cordobans successfully defended their new home for well over 100 years.  During that time, they launched raids across the Aegean sea, and occupied several smaller islands nearby.  It wasn't until 961 that Nikephoros II Phokas, one of the great generals of Byzantine history, and later a Byzantine Emperor, was able to retake Crete and drive the Cordobans out for good.  Today, over 1,000 years after their defeat, Chandax (now called Heraklion) remains the capital of the island.

Trapezium Nullis

If you want to start your own country, it's tough to find any land to lay claim to.  The entire map is painted one color or another, so unless you want to try your luck in the frigid wastes of Marie Byrd Land in Antarctica, or look for an abandoned ocean platform like Sealand, the prospects look pretty grim.

However, thanks to the wonders of international politics and border disputes, there is one patch of land that no one seems to want.  As with all border issues, the problem can be traced back to the British.   At the end of the 19th century, the British had control over the area, and they decided that the border between the region administered from Cairo and the region administered from Khartoum should be a straight line.  Any third world country which has a straight-line border drawn by a British cartographer has probably run into issues with it, and in this case the British themselves found a problem.  There's a triangle of land along the coast of the Red Sea which is closer to Khartoum and to Cairo, but was North of their line.

So, 3 years later, they drew a new line, this one dipped a bit below the old line, and then rose back above it to place that triangle under Khartoum's authority.  The area in that little dip is called the Bir Tawil Triangle (despite being roughly a trapezoid).  Fast forward to today, and both countries want the valuable Red Sea coast line, and couldn't care less about Bir Tawil.  Egypt claims the original straight line border, which places the coast line on their side, and gives Bir Tawil to Sudan, while Sudan claims the revised border, which does the opposite.  Both sides vehemently insist that Bir Tawil does not belong to them (as accepting it would mean ceding the much more valuable territory), and it is therefore essentially the last unclaimed habitable territory in the world.