Mazar-e-Sharif guards Afghanistan's northern plains. Built around a magnificent blue-tiled mausoleum - or mazar - reputed to be that of Ali, it is one of Afghanistan's four great cities. It sits astride the ancient trade route between Central Asia and India.
If Mazar-e-Sharif were to fall to the anti-Taleban opposition it would provide them - and potentially even American forces - with a powerful base from which to consolidate control over all of northern Afghanistan. The Taleban have controlled Mazar-e-Sharif for the past four years, but it isn't natural territory for the purist Pushtun militiamen. Mazar's people are mostly Uzbeks and Tajiks. They speak Persian and, before the Taleban's arrival, they'd become used to a relatively liberal lifestyle under their one-time communist leader, the warlord Abdur Rasheed Dostam.
Dostam has a record of switching sides when convenient, and there are many Taleban supporters who would do likewise if the fortunes of the puritan militia are on the decline.