The Origins of Black Tea

The resulting tea would simply keep longer and could therefore be shipped further, both by land and by sea. Meanwhile, green tea bricks more easily suffered from overheating from freezing and they often developed mold in damp environments. So yeah, we get into the situation where the farther out you're sending your tea, the more it makes sense for it to be black tea. And yet at the same time, there seems to have been at least a mild panic in Britain in the 19th century about green tea - making people hallucinate unlike proper black tea.