Bronze Age Fire Offering Rituals in the Chengdu Plain: Archaeobotanical Evidence From the Ashy Layer of Pit No. 4 in Sanxingdui's Sacrificial Area

ABSTRACT The ash layer of Pit No. 4 at Sanxingdui offers a rare field case for investigating fuel‐related behaviors in Liao sacrifice during the late Shang period. Analyses of charcoal, seeds, and phytoliths from 71 samples indicate that bamboo charcoal was the dominant fuel source, with only small amounts of Phoebe sp. and Pistacia chinensis attested. This narrow range of fuels stands in stark contrast to the high diversity of firewood used for nonritual purposes during the same period, indicating deliberate selection. Bamboo may have been chosen for its local availability, while Phoebe and Pistacia chinensis were likely selected for their smoke‐producing properties and yellow/golden hues, which align with the ritual functions of communicating with deities as well as the symbolism of sun–gold worship at Sanxingdui. Evidence from numerous sources indicates that the ash layer is highly likely the residue of a Liao sacrifice. The ritual site was probably located in an area with sparse vegetation or had been deliberately cleared beforehand; the fire stack was constructed primarily with de‐leafed bamboo culms, mixed with small quantities of Phoebe and Pistacia chinensis , and after ignition, the smoke and fragrance helped create the ritual atmosphere. This study presents the first systematic reconstruction of fuel selection and behavioral sequence in the Sanxingdui Liao sacrifice, revealing a distinctive bamboo‐dominated regional custom, also suggesting that multiproxy analysis can provide effective pathways and methodological support for empirical research on Liao sacrifice.