The Sacrificial Horse Pit of Qi
Photograph of skeletons lined up in the "Sacrificial Horse Pit", a burial site within the tomb of Duke Jing of Qi. Jing reigned from 547 to 490 BC in Qi, an ancient Chinese state located in present-day Shandong. The pit was first discovered in 1964 when archeologists came across 145 horse skeletons while excavating the northern side of the tomb.
As described in Wikipedia:
"The pit for the sacrificial horses is 215 metres (705 ft) long, wrapping around the tomb on three sides. In 1982, archaeologists excavated a further 36.5 metres (120 ft) of the pit and unearthed 106 more horse skeletons. The tomb has not been completely excavated, but archaeologists estimate that more than 600 horses were buried in total, making it by far the largest horse sacrifice site discovered in China.
The horses were between the ages of five and seven when they died. It is believed that they were killed by strikes on the head after being fed alcohol and falling unconscious. Also found in the tomb are 30 sacrificial dogs, two pigs, and six other domesticated animals."