After three hours trudging along steep forest paths, you come to a surreal sight. Hundreds of megalithic stone jars, large enough for someone to a crouch inside, are strewn all around. This group of 416 jars is the largest at the aptly named Plain of Jars, whose current tally stands at 1900 jars in 52 clusters, plus fifteen jar-making sites. They were made by a vanished civilization and their presence indicates that the mountains were prosperously settled at the time. Today the Xieng Khoung province is on the rise again, this time as a tourist hub.

Little is known about the jar-makers, except that the plateau was a strategic and prosperous centre for trade routes extending from India to China. Nearly 2000 years ago, possibly earlier according to new evidence, these jars functioned as mortuary vessels: a corpse would be placed inside the jar until it decomposed down to its essence, then cremated and buried in a second urn with personal possessions. Now all that remains here are the empty jars, set in clusters on the crests of hills, an imposing and eerie legacy.

At Phukeng, you can see where the jars were made. Dozens of incomplete jars lie on the mountainside where they were abandoned after cracking during construction. It’s a sight that evokes the magnitude of the effort: after many weeks spent gouging a jar from a boulder with hammer and chisel, the creators then had to haul the load of several tons (the largest jar weighs six tons) across the undulating, grassy, pine-studded landscape to the “cemetery” 8km away. How the jars were transported is another puzzle that serves to deepen the enigma that pervades the Plain of Jars.

Daily public buses connect Luang Prabang and Vientiane with Phonsovan. Auberge de la Plaine des Jarres ([email protected]) is the province’s best hotel, with private wooden bungalows.