In ancient Chinese, the word "green" sometimes means black. What happened? Didn't China have the word "black" in ancient times?

Blue means blue in ancient times. Xunzi's "Encouraging Learning": Qing, taken from Qing and shine on you. Some people say that shine on you is better than blue. In ancient times, the word blue did not refer to color, but to an herb from which blue dye could be extracted.

Blue also means dark green. Liu Yuxi's Humble Room Inscription: The grass is green in the curtain.

Blue also means blue. Du Fu's quatrains: Walk by the river, see you later.

However, I really haven't seen the usage of black in ancient Chinese, and I haven't found such an example in ancient Chinese dictionaries.

Where did the landlord say this? Please give me your advice. Can you give me some examples to answer?