Xinzheng to Tash Rabat

Welcome, traveller! This journey will take you 4500 years, and 5000 miles from China to the West along the Silk Road. The Silk Road shaped the world we live in today, and we'll stop at key points along the route. And it all starts with a single moment.

It is 2640 BC and the Yellow Emperor's wife, Lady Xi Ling Shi, is taking tea in the shade of a mulberry bush. A silkworm cocoon falls into her tea, and she notices how the fibres unspool in the hot liquid. This is silk, a thread produced by the larvae of the bombyx mori moth. A single silkworm can produce over 900 metres of silk. Soon this fibre is being woven into fabric.

It is 102 BC and silk is a valuable commodity. Smuggling silkworms out of China is punishable by death. Emperor Wudi's kingdom is rich with silk, but he needs horses for his armies to fight the warring nomads beyond his borders. He sent General Li Guangli to retrieve "heavenly horses" a year ago, and he is returning with 1000 of them! The General struck a deal to sell silk to the tribes to the west, in return for horses. This is the birth of the Silk Road.

X'ian is the Eastern terminus of the Silk Road, and it has grown rich from trade. You arrive at the Scarlet Bird Gate to join a camel caravan travelling along the Gansu corridor between the Tibetan plateau and the southern deserts. Without the camels this journey would not be possible.

It's AD 440 and you're 1000 miles to the west of X'ian. You're travelling to the oasis town of Dunhuang – one of the most important centres of Buddhist learning in the region. A Buddhist monk shows you around a nearby cave network where a large Buddha statue sits. This is the Maitreya Buddha. The sculpture style was learned from Buddhist travellers from Afghanistan. The monks are collecting the teachings of Buddhism and writing them down, so they can travel to the rest of the world.

You're 2000 miles west of X'ian at the edge of the desert. You switch camels for yaks, and head into the mountains. After two days you reach Tash Rabat, a caravanserai, where you hear news about a battle at Talas. The Chinese army has been defeated by the Arab Abbasid Caliphate. Change is afoot!