Alexander the Great, Genghis Khan, and that's pretty much it.

If you read Afghanistan's history, the only men to conquer this essentially landless region were Alexander the Great and Genghis Khan. Everyone else pretty much failed miserably. Tom Friedman references that with yet another excellent column in today's New York Times:

"Last week, I toured the great Mogul compound of Fatehpur Sikri, near the Taj Mahal. My Indian guide mentioned in passing that in the late 1500s, when Afghanistan was part of India and the Mogul Empire, the Iranian Persians invaded Afghanistan in an effort to “seize the towns of Herat and Kandahar” and a great battle ensued. I had to laugh to myself: “Well, add them to that long list of suckers — countries certain that controlling Afghanistan’s destiny was vital to their national security.”"

The rest of Friedman's column is worth reading as well.