I have pulled together a few resources on the pre-modern use of Cannabis in various cultures, including 19th- and early 20th- century American medicine. Doctors and herbalists of all stripes regularly prescribed Cannabis until the 1930s in the US. Prescription by MDs continued in some parts of Europe straight through the era of prohibition. As noted in an earlier post, cannabis flower was not widely used in mainstream Chinese medicine. The typical indications listed in herbal texts over the centuries suggest a low-THC, CBD hemp variety. However, it was widely used throughout East Asia, including in China and India. All of these source make it clear that the mind-altering properties of cannabis were well-known — and used — at least for recreational and religious purposes.
Here are a few curated resources on pre-modern use of cannabis that are clearly referring to varieties with appreciable THC content:
Eclectic and Other 19th Century Herbals – If you are not familiar with the Eclectic School of Herbalism, take some time to read these sections. The level of detail in the descriptions of medicinals in their materia medicas￼ is remarkable.