Museums have been the playthings of nations for as long as they've been open for business. Even if the First Emperor wasn't an exhibition about state unification, it wouldn't take a genius to work out that a year before the Beijing Olympics these are warriors turned global ambassadors.

I didn't expect the British Museum to provide a leaflet on heritage diplomacy. But neither did I expect an exhibition swinging between two styles of curation, one of which appears to be as archaic as the relics, and brings with it a whiff of propaganda.

It opens, "The First Emperor was one of the world's greatest rulers. Over 2,000 years ago he founded what was to become the nation of China". One interpretation, sure, but I feel uneasy at the emphasis on progress over disruption and tyranny.

It is tempting to see the display of artefacts leading up to the warriors as mere padding. Look again. Weapons and bowls are reduced to their technological functions and dimensions. Such bland accounting is a common feature of Chinese museums. Winding its way through warfare, writing, weights and measures, the display is not only patronising, it validates a continuous story of technological development and a powerful past for modern China. When you're told, "the Chinese" have been crafting objects since Neolithic times, it's like saying "the English" built Stonehenge.

Reaching the warriors and some of the most recent finds, however, the tone changes dramatically. The authoritarian "This is ..." becomes "We think ...". The archaeological process is given weight, introducing distance between the people of the past and the present. Jade tiles, found individually in a messy heap, have been pieced back together into suits of ritual armour - a reminder that everything is the work of representation and reconstruction.

Was it necessary to incorporate two display styles to sweeten Chinese-British relations? As it is, one diminishes the other.

The First Emperor is at the British Museum (020 7323 8181, www.britishmuseum.org) until 6 April 2008. Fiona Parrott is an anthropologist at University College London.