What was the name of the place where Four Treasures of the Study was sold in ancient China? Research? Or in a grocery store or a calligraphy and painting shop?

I see. I misunderstood. I'm not particularly sure. It may be better to consult some museums or collectors. In my opinion, this Four Treasures of the Study should be sold in ordinary shops in ancient times. Generally speaking, they may be sold separately. Some shops specialize in pens, while others specialize in inkstones. In ancient times, there was no such detailed division of labor as modern people. Four Treasures of the Study enjoys different reputations all over the world. Perhaps some areas are mainly pen shops, while others are mainly paper shops, and there will be no special trading gathering points like this. I suggest you ask an antique collector. These questions are too professional.