Cauldron of conflict at Asia's crossroads ia

Afghanistan's importance as the crossroads of Asia has given it an externally imposed appearance of unity it does not really possess. That, and not any native predilection for violence, is the main reason why it has been fought over fairly constantly for thousands of years.

As a British observer wrote in 1901, "We have contributed much to give a national unity to that nebulous community which we call Afghanistan by drawing a boundary all round it and elevating it to the position of a buffer state between ourselves and Russia".

Arnold Toynbee called it a roundabout rather than a crossroads, around which a procession of peoples passed from Central Asia or Iran en route to the plains of north India. The often disastrous British interventions were to prevent Russia, which had designs on India, achieving a foothold.

But that external interest helped to forge Afghan unity - and Afghan isolation. The 1979 Soviet invasion was similarly motivated, by fear, in Brezhnev's words, "that Afghanistan would ... be turned into an imperialist military bridgehead on our southern border". The different groups in Afghanistan never wanted that externally imposed unity and sided with external neighbours in their internal quarrels.

Afghanistan was, in the words of Abdur Rahman, who imposed unification 1880-1901, "like a goat between two lions, or a grain of wheat between two strong millstones". How, he asked, can it "stand in the midway of the stones without being ground to dust?" The stones have now been removed, but Afghanistan continues to grind itself into dust.

The fighting since the 1989 Soviet withdrawal has seen many alliances between different factions, often for short-lived, tactical reasons. The constituencies of the groups broadly follow the country's ethnic make- up. Ethnic divisions often reinforce differences between moderates and more radical Islamic groups, and also between Sunni Muslims and the Shia minority. The biggest ethnic group is the Pathans, who make up 40 per cent of the population. The Tajiks, the second-largest group, have a proverb: "Trust a snake before a harlot, and a harlot before a Pathan."

The Taliban, "seekers of religious knowledge", who are mostly Pathan and fundamentalist Sunnis, seized Kabul last month.

This brought three-quarters of Afghanistan under their control but took the predominantly Pathan Taliban well outside their ethnic power-base.

Other influential groups include Burhanuddin Rabbani's Jamiat-i-Islami, based on the Persian-speaking group and which comprises a quarter of the population; and Abdul Rashid Dostam's Jumbesh-i-Milli, which controls most of northern Afghanistan. It is mainly secular, supported by Uzbeks. Ahmed Shah Massoud, Mr Rabbani's military commander, has sided with General Dostam against the Taliban.

International concern about Afghanistan is now motivated by what the country produces: drugs and violence.

The UN estimates that it produced 2,400 tons of opium last year. It is also a potential route for oil from Central Asia, avoiding lines through Iran, which are problematical, and Grozny, which is even more so. But until stability returns, there is no prospect of secure pipelines running through.

Other countries are still interested in Afghanistan, for new reasons.