A 6th century limestone figure of Buddha is expected to make $800,000-1.2m at Sotheby's.
The lot is set to top the Images of Enlightenment: Devotional Works of Art and Paintings sale in New York on September 16.
The piece was created in the upper Huanghe region of China at the time of the Eastern Wei dynasty (534-550 AD).
Buddhism arrived in China in the 1st century AD, but only exploded in popularity during the 4th century. Around this time vast numbers of temples and monasteries were built.
Sotheby's explains: "It is extremely rare to find a sculpture of the Buddha with this restrained beatific smile incarnating the bliss of enlightenment, which was rendered in stone for only a very short period and can be deemed the most moving and alluring and thus most desirable expression of a Buddha image.
"It is also extremely rare to find a stele of this large size and exquisite craftsmanship."
A Chinese sandstone figure of Avalokiteshvara dating to the end of the 6th century carries an identical estimate of $800,000-1.2m.
The figure is a key bodhisattva who stands for compassion.
The auction house comments: "This majestic, solemn Avalokiteshvara figure embodies the classic features of Northern Qi Buddhist sculpture."
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