Clare Nuttall in Almaty -

The five Central Asian republics have entered their third decade of independence, confounding predictions that they wouldn't survive after the break-up of the Soviet Union. But they are under new pressures from outside as China and Russia seek to extend their spheres of influence, while tensions between the states remain as strong as ever.

Within the region, historical differences have been exaggerated by post-Soviet nation-building efforts, which have created conflict across borders that had deliberately divided ethnic groups. Meanwhile, the modern day phenomena of fast growing populations and climate change is leading to growing competition for limited resources.

Economically, the paths of the Central Asian republics have also diverged enormously. Kazakhstan's oil wealth has been used to diversify the economy, putting it on track to become a middle-income country by 2016. Turkmenistan has the world's fourth largest gas reserves, but President Gurbanguly Berdymukhamedov has done little to develop other sectors of the economy. Uzbekistan could be the region's economic powerhouse, given its 28m population and strength in agriculture, which should form the basis of a diversified economy. The only "stan" to border all the others, it is also a natural manufacturing and distribution hub. But during 1990s, Uzbekistan subsisted on cotton exports, and despite diversifying into auto-making, gold production and food processing, progress is held back by the iron grip of President Islam Karimov. Neither Kyrgyzstan nor Tajikistan has a similar level of resources, raising the question of whether they are economically viable at all. The question is especially poignant for Tajikistan, the poorest post-Soviet country, which has lurched from crisis to crisis and now catastrophe.

The Ferghana fault line

At the heart of Central Asia is the fertile and densely populated Ferghana valley, which was carved up between the Kyrgyz, Tajik and Uzbek Soviet Socialist Republics (SSRs) in the 1920s. Josef Stalin's nationalities policy was deliberately designed to avoid creating ethnically homogenous republics that might make a bid for self-determination and independence from the newly created Soviet Union. To this end, Samarkand and Bukhara, both ancient Tajik cultural centres, were placed in the Uzbek SSR, while the Kyrgyz SSR got the mainly Uzbek cities of Osh and Jala-Abad.

These borders were never intended to separate independent states, and became flashpoints for ethnic conflict in the last years of the Soviet Union, even more so since then. Hundreds of people died in ethnic clashes in Uzgen, south Kyrgyzstan, in 1990. Two decades later, in June 2010, a dispute between ethnic Kyrgyz and Uzbek youths in Osh escalated into four days of violence that spread to towns across south Kyrgyzstan. At least 400 people, mainly ethnic Uzbeks, were killed. Some 18 months on, buildings are being rebuilt but the wounds have not healed, largely because of the subsequent actions of the Kyrgyz authorities. According to Human Rights Watch, most of those arrested during police investigations have been ethnic Uzbeks, many of whom were tortured in custody.

Border controls have been tightened in recent years. Most crossings between Kyrgyzstan and Uzbekistan have been shut, leading to a thriving illegal and dangerous trade in the smuggling of people and goods. The eight tiny enclaves within the Ferghana valley have been a further source of tension, with frequent stand-offs over issues such as water use and grazing rights.

Nation building on the Steppe

In the early 1990s, the Central Asian governments pursued some fairly aggressive nation building - leading, for example, to the somewhat spurious identification of modern day Uzbekistan with Amur Timur and Tajikistan with the Somonid dynasty. This changed the way people identified themselves, aggravating the mood in the ethnically mixed border areas. "Nation building matters. People see themselves differently, and are more aware of their differences," says Christine Bichsel, senior researcher at the Swiss University of Fribourg.

Nation building was a particular priority since the new Central Asian states were not natural constructs drawn along either ethnic or geographic lines. Kyrgyzstan is sliced in half by the Ala-Too mountain range, which divides the nomadic north from the Ferghana Valley. Kyrgyzstan's 2005 and 2010 revolutions both pitted southern against northern clans. With many of Tajikistan's dilapidated roads impassible in winter, distinct regional economies have emerged.

All the Central Asian republics except Kyrgyzstan are held together by authoritarian leaders. With Kazakhstan's Nursultan Nazarbayev and Uzbekistan's Karimov both in their 70s and without obvious successors, fears of future political turmoil are growing. If the official polls are to be believed (and they are not), Nazarbayev is by far the most popular leader in the Commonwealth of Independent States, but his popularity is largely driven by fear of what comes next.

Meanwhile, the Tajik government's difficulty in providing even basic services to its population has pushed Tajikistan into the arms of its rich and powerful neighbour China. Soft loans have funded an overhaul of Tajikistan's roads, carried out entirely by crews of Chinese workers, housed at massive camps flying the red flag. Tajikistan's mining assets have been snapped up by Chinese investors. In future, Tajikistan may have to make further concessions to Beijing - including, potentially, acceding to territorial demands - if it is unable to keep up loan repayments.

However, Central Asia traditionally falls within the Russian sphere of influence and Vladimir Putin's efforts to extend the Customs Union south show Moscow is not going to concede without a fight. Frederick Starr, chairman of the Central Asia-Caucasus Institute, says the region is "under relentless pressure" from Russia.

Russia continues to flex its muscles over its small satellites. When a Tajik court convicted Russian pilot Vladimir Sadovnichy of smuggling, the wholesale expulsion of Tajik migrants from Russia swiftly followed, and Tajikistan President Emomali Rakhmon was quick to back down. Russia was the major influence in the 2010 Kyrgyzstan revolution, backing the opposition after former president Kurmanbek Bakiyev took funding from Russia then reneged on a promise to shut the US airbase near Bishkek. "There is no other area on earth that is surrounded by nuclear powers, or where so many major powers consider they have an inherent right to interfere in the region's affairs," says Starr, adding that in spite of all this, "Central Asian foreign policy has proved to be effective."

In addition to pressures from outside, internal factors are pushing the Central Asian region closer to conflict. Populations are increasing rapidly due to high birthrates. At the same time, global climate change is gradually reducing the amount of land and water available for farming. Kyrgyzstan and Tajikistan have experienced some of the world's biggest price hikes for basic foodstuffs, according to the World Food Programme.

Water torture

The biggest cause of tension is water. Angry words have been exchanged between Tajikistan and Uzbekistan over Tajik plans to build a massive new dam at Roghun on the Vakhsh river, which Uzbekistan fears will disrupt water supplies for its cotton industry. In an attempt to pressure Tajikstan into abandoning the project, Uzbek officials for more than a year have held up freight trains bound for Tajikistan.

A 2010 Oxfam report predicts that 30% of Tajikistan's glaciers will melt by 2050. Andy Baker, Tajikistan country director at Oxfam, warns of a "dangerous ripple effect," with countries across Central Asia "potentially wrestling over dwindling water resources in coming decades." Given that most border disputes start over shared resources, conflicts are likely to become evermore frequent and serious as competition for limited land and water becomes more intense.

With all these contentious issues, perhaps the real question is, why has the Ferghana valley not erupted into war already? There seems to be a feeling among even the most unreasonable and nationalistic of leaders that preserving the peace is preferable. In one notable example, after the Osh events of June 2010, Karimov held back from retaliation against Kyrgyzstan for its treatment of ethnic Uzbeks. And as Bichsel points out, issues of vital importance in the border areas are not taken so seriously at state level, where the priority is more often to preserve the peace.

Heated exchanges over water and energy management, cutting off of gas supplies, and economic disruption can all be interpreted as steps in a complex dance that is well understood to the participants. "Observers in other parts of the world are very quick to interpret about water issues and they ignore firstly that each side has legitimate concerns, and secondly that they all know each other much better than we know them after living alongside each other for centuries," says Starr.

Although there are ongoing conflicts that may get worse, and emerging problems as resources become scarcer and will have to be shared among more people, the risk of large-scale war is not imminent. And with Russia and China providing a balance to each other in their influence on the region, the Central Asian republics are not set to disappear from the map any time soon.