The leaders of Pakistan and Uzbekistan have signed a number of agreements and pledged to fight terrorism together.
Pervez Musharraf wants to do business in Central Asia
Pakistani President Pervez Musharraf, making the first visit by a Pakistani head of state for almost a decade, welcomed "a bright new future".
The nations have been forced to work together as they try to combat Islamic militants in the Pakistani borderlands.
Mr Musharraf was also due to visit the ancient city of Samarkand, before moving on to neighbouring Kyrgyzstan.
During talks in Tashkent, Mr Musharraf and Uzbek President Islam Karimov discussed efforts to hunt down militants in Waziristan on the Pakistani border with Afghanistan.
They are thought to include Tashkent's most wanted enemy, Tahir Yuldash, a young radical and ally of the former Taliban regime in Afghanistan.
Mr Musharraf said: "We know that Pakistan has some Uzbek terrorists in its area and I have assured the president that Pakistan will not allow the use of its soil by any terrorists from Uzbekistan against your national interests."
He called for "a very effective extradition treaty" between the two lands.
Mr Karimov said "Musharraf's government shows real bravery," in its war against militants.
Throughout the 1990s, Uzbek-Pakistani relations soured.
Islamabad and Tashkent backed opposing factions in Afghanistan.
But now both have signed up to the US-led "war on terror", and have given their support to the new government in Kabul.
Another important focus of the talks was trade. With peace restored in Afghanistan, both Pakistan and Uzbekistan are anxious to build trade routes across the country, giving Pakistan an entry to the markets of Central Asia, and landlocked Uzbekistan access to the ports of the Indian Ocean.
The two leaders signed a number of bilateral agreements.
Mr Musharraf is due to head next to Kyrgyzstan, visiting the capital Bishkek and some of the country's historic sites, Kyrgyz officials said.