How tastes change. By the time the panels were excavated four to five decades ago, Chairman Mao had banned traditional erotica as pornography. During his Cultural Revolution the Red Guards burned such works in bonfires. The only reason the panels survived was that a peasant had used them in what the radicals saw as a more noble project: a pig sty. Recovered by sharp-eyed local officials in the 1980s, they have often been shown abroad, but never before in China. Art professor Liu Dalin of Shanghai University says they are among “the finest examples of China’s rich erotic art,” and a reflection of “very lively” sex lives during the Han period. The display in the hinterlands of Sichuan province hints at lingering official embarrassment. But thousands of tourists have trekked out to Xindu, suggesting a popular yearning for the good old days.