Key concept of math may have emerged first in China

The discovery of ancient counting rods made of ivory suggests that the Chinese may have been the first in the world to conceive of negative and positive numbers — 800 years earlier than India — according to recent research.

Sixty-one rods were unearthed between 2004 and 2008 in Xi'an, Shaanxi province, at the Qin Mausoleum of Shenheyuan for royalty during the Warring States Period (475-221 BC). They range in length from 18.3 to 18.5 centimeters and have a diameter of 0.49 to 0.54cm. Each weighs about 5.7 to 7.7 grams.

After years of research, experts have concluded that the ivory rods were likely to have been one of the earliest counting tools used to distinguish the concept of "positive" and "negative".