Yemen, the ancestral homeland of Osama Bin Laden, whose tribal revolts and blood feuds exhausted every imperial overlord from the Roman Caesars and the Ottoman sultans to the modern British empire and the Soviet Union, is a land haunted by its own tortuous past. Aden was once the capital of the only Marxist-Leninist state ever to emerge in the Arab world. Sanaa was ruled by a Zeidi Shia imamate whose pedigree went back a thousand years before its overthrow by a cabal of republican military officers inspired by Egypt’s President Nasser in 1962. The barren valleys of the Hadhramaut produced spice traders who spread Islam in Malaya and the Indonesian archipelago, warriors who guarded the thrones of the Hyderbadi Nizams, Egyptian Pharaohs and medieval Delhi sultans, money changers like the Bin Mahfouz and Kaki clans who built billion dollar banking empires in Saudi Arabia. The Roman historian Suetonius called Yemen “Arabia Felix,” the Sabean kingdom is mentioned in the cuneiform stone tablets of the Assyrians and the Bible’s Book of Kings, the Queen of Sheba (the Quranic Bilqis) traveled  to the court of King Solomon’s Judea with a camel caravan of silver and frankincense, the hard currencies of the ancient world.

Yemen now faces its most ominous geopolitical convulsion since President Ali Abdullah Saleh’s northern troops vanquished South Yemen’s rebel tribes in 1994 in a short, savage war. President Saleh, a military dictator since 1978 whose two predecessors were both assassinated, faces another secessionist revolt in the south he unified in 1990 into a single state as well as a full scale civil war with the Houthi rebels in Saada Province. Meanwhile, Yemen has replaced Afghanistan as the regional epicenter of Al Qaeda, whose suicide bombers recently targeted both the US Embassy in Sanaa and a senior prince of the House of Saud in his Jeddah palace. Now Saudi Arabia is an actor in the Yemen civil war.

The Arab world, particularly Saudi Arabia and the GCC, cannot allow Yemen, the poorest country in the Arab world, to be dismembered, become a failed state like Somalia or Afghanistan. After all, Yemen straddles the naval choke point of the Bab Al Mandeb, a gateway to the Red Sea oil tanker shipping routes and the Suez Canal. Several million Yemenis work in Saudi Arabia, whose Najran, Jizan and Asir provinces have tribal links with Al Qaeda zealots. The Yemeni civil war is the greatest national security threat to the Saudi kingdom and the GCC states since Saddam Hussein’s invasion of Kuwait, the fall of the Shah’s regime in imperial Iran and the Dhofar tribal revolt in Oman. Strangely, the wider Arab and Islamic world has done almost nothing to end a war that has claimed thousands of lives, that could condemn Yemen to a murderous chain reaction of ethnic horror shows as in Iraq, Palestine or Bosnia, that could literally change the history and balance of power in the entire Middle East.

It is a tragedy that a land whose pre-Islamic merchant kingdoms were once the Monaco and Dubai of the ancient world, whose Marib Dam awed Roman and Byzantine engineers and is still used to supply clifftop villages with water two millennia after it was built, whose port of Aden was the naval outpost of Britannia’s jewel in the crown Indian Raj, is so poor that half its women are illiterates, a third of its children are malnourished. The Yemeni diaspora extends from the Jumeirah of my boyhood to the cities of the Hijaz, Oman and the Gulf, to Michigan, Brooklyn, and South London.

When the Mongol hordes vanquished the Abbasid empire and sacked Baghdad in 1258, Yemen was the repository of Islamic science, culture and medicine. I was stunned by the visual beauty of Yemen, the stone fortresses perched on strategic wadis, the terraces sculpted from mountains centuries ago to catch precious water. (But Yemen is running out of both oil and water, an ecological time bomb is ticking away almost unnoticed in the UAE media), the tribal tournaments as exotic as anything I ever saw in the Scottish Highlands or pre-Taleban Swat.

The Prophet Muhammad, peace be upon him, praised the generosity and hospitality of the Naas qabili, the tribal people of Yemen, who have resisted the authority of every ruler in Sanaa and Aden, from the Ottomans to the British, from the Marxist Politburo of the defunct Peoples Democratic Republic of Yemen (PDRY) to President Saleh.

In Yemen, as elsewhere in the Arab world, the political pathologies of 2009 are rooted in the complex maze of the past. President  Saleh’s unification of the north and south in 1990 took advantage of the collapse of the USSR, a green light from Riyadh, Washington (and above all, Baghdad). Ali Saleh was financed by Baathist Iraq, the reason he did not condemn Saddam’s invasion of Kuwait, an act that led the enraged Saudis to expel a million Yemeni guest workers. The 1990 unification of Yemen was deeply flawed.

Yemen’s regime is notoriously autocratic, a model of the mukhabarat (intelligence) state. Ali Abdullah Saleh’s sons, brothers and nephews run all major Yemeni military secret police and counter-terrorism organs of the state, another classic Arab jumluka (republican kingdom). The northern elite’s attempt to monopolise Aden’s oil, smuggling and trade wealth meant the south never accepted the rulers of Sanaa, who the Adenis call “atrack” or Ottomans.

The regime used Afghan Arabs to pillage the south in 1994, a hundred Yemenis languish in Guantanamo Bay and President Saleh’s alliance with Washington to hunt Al Qaeda cells is deeply resented by the Yemeni tribes.

The Zaidi Shia, followers of the slain rebel Hussein Houti, have accepted weapons and cash from Teheran and Moqtada Al Sadr’s Jaish Mehdi militia in Iraq, meaning Yemen has joined Lebanon and Iraq as yet another proxy battlefield between Saudi Arabia and Iran, the superpowers of the Islamic world. The World Bank estimates that almost half of all Yemenis live in dire poverty but Yemenis comprise half the population of the Arabian Peninsula. Aerial bombardments, blockades and massacres alone will not end the revolt in Saada Province and Aden. The statesmen of the GCC must defuse the national security time bomb in Yemen before it is too late.

Matein Khalid is a prominent investment banker based in Dubai