Because I thought you were obviously wrong about the 7000 years thing, here's a history of trademarks by some guy named Olivier Pierre:

Since ancient times, merchants have been using signs or marks in trade to distinguish their products. Registrations came much later, in the 18th century with the establishment of Intellectual Property Offices.

[...]

The use of trademarks dates back thousands of years, however we can’t date their origins with precision. Some of the earliest forms of identification of marks date from Prehistory. For instance, the Lascaux cave paintings in France show bulls drawings with marks on them. Experts believe that people were using personal marks to claim ownership of livestock, long before literate societies. That was about 15.000 years ago.

The Egyptian masonry from some 6,000 years ago shows distinguishable quarry marks and stonecutters signs, to identify the source of the stone and the laborer who carried out the work to claim their wages. There were creative entrepreneurs who marketed their goods beyond their localities and sometimes over long distances. Wine amphorae marked with seals were found inside the Tomb of the pharaoh Tutankhamun who reigned between 1336 a.c. to 1327 a.c. over ancient Egypt.

I've gotten so used to think of trademarks as registered trademarks, but it makes sense that it has existed much longer in the literal sense. The earliest known law however dates back little more than 4000 years, and there's nothing about trademarks there, so I think it's fair to say trademark law is a lot more modern. :)

Sorry for being entirely off-topic.