^^Right!
High-potency strains have existed in remote corners of the world for aeons, but it's just in the recent decades that it was possible for interested pot lovers to track them down and start working with them- a few inventions have greatly improved that: The airplane, the hippie, the Beatles and their popularisation of all things Eastern and exotic, the HID light, etc... hahaha
So we have to thank decades of travellers for bringing back the seeds that have increased out THC levels in modern weed!