They didn’t have a word for blue?
https://www.grunge.com/285728/the-real-reason-ancient-people-didnt-see-the-color-blue/
In Vietnamese the words for blue and for green are both xanh. When they are distinguished, green becomes xanh lá cây = green/blue-leaf-tree and xanh = blue/green = xanh như trời = blue/green like sky. Pronounce like sine la cay and sine nyi choi.
Correct. You would not see blue ender a purple sky....