^"Laozi". Stanford Encyclopedia of Philosophy. Stanford University. 2018. The discovery of two Laozi silk manuscripts at Mawangdui, near Changsha, Hunan province in 1973 marks an important milestone in modern Laozi research. The manuscripts, identified simply as 'A' (jia) and 'B' (yi), were found in a tomb that was sealed in 168 BC. The texts themselves can be dated earlier, the 'A' manuscript being the older of the two, copied in all likelihood before 195 BC.
"Until recently, the Mawangdui manuscripts have held the pride of place as the oldest extant manuscripts of the Laozi. In late 1993, the excavation of a tomb (identified as M1) in Guodian, Jingmen city, Hubei, has yielded among other things some 800 bamboo slips, of which 730 are inscribed, containing over 13,000 Chinese characters. Some of these, amounting to about 2,000 characters, match the Laozi. The tomb...is dated around 300 BC.