Countries around the world are in the process of vaccinating their populations against Covid-19, or working out plans to do so, and many hope that it will bring an end to the pandemic. With more people getting inoculated, the next step may be “ vaccine passports ”, which could allow people who have been vaccinated against the coronavirus to cross national borders without the considerable cost of quarantines on both ends of an overseas trip. Before the modern era, when international travel was prohibitive because of distance, inconvenient transport and expense, most people did not travel abroad. Hence, papers that identified the bearer’s identity and nationality were not common. That said, people who had to cross internal and international borders for official, mercantile and other purposes required some form of official documentation. In pre-imperial China, when the country was divided by the Zhou dynasty (1046-256BC) into feudal domains, people who travelled from one state to another, or even between locations within the same state, had to prove their identities at checkpoints using various tokens issued by state governments. In the beginning, these were made of jadeite and bronze, but as more officials, merchants and couriers travelled longer distances, they were replaced with wooden or bamboo ones. In 298BC, when Lord Mengchang was fleeing the state of Qin, whose king wanted to kill him, the nobleman got past the guards at the checkpoint by altering the name on his identification token. This was one of China’s earliest documented forms of passport. By the Tang dynasty (AD618-907), the cosmopolitan nature of the Chinese empire necessitated a more comprehensive system to manage people going in and out of the country. To ensure the proper conduct of trade, prevent non-payment of excises and safeguard national security, all travellers had to bear official papers that identified them, the places they had visited and their purpose of visit. Buddhist monk Xuanzang (AD602-664), immortalised as the master of the Monkey King in the novel Journey to the West , was an “illegal”. Contrary to the fictionalised account, he travelled across and exited China illegally when he became impatient with the delay in issuing his travel document. His 16-year sojourn, from AD629, in Central Asia and the Indian subcontinent, during which he acquired more than 650 Buddhist scriptures, was an important chapter in the history of Buddhism in China. The 1689 Treaty of Nerchinsk, signed between Russia and Qing-dynasty China to demarcate the border between the two nations and open up bilateral trade, stipulated that people in both countries could cross the border to trade provided that they possessed the necessary papers. The Latin, Russian, Manchurian and Chinese versions of the treaty, which differed considerably in certain details, all mentioned a document that was required for a person from one country to enter the other. After the Chinese monarchy was overthrown in 1912, the Republic of China issued the country’s first modern passports in the form of a loose leaf of paper. The first booklet-type passport was issued in 1922, containing 16 pages with a validity period of three years. Like most people in the world, I have not travelled for over a year. Apart from the fevered desire to go on holiday overseas, I have not seen members of my family and some of my friends for far too long. I can’t wait to use my passport again.