Boko is a tricky word. It refers to books in the general sense of collected knowledge. More specifically collected western knowledge of science, culture, government, and art.
Not just books are forbidden. Any knowledge that “corrupts” Islam.
If that knowledge is in your head... goodbye head.
6th Century Islamic edict: If something is in the koran, it is unneeded - burn it. If something is not in the koran - it is anathema - burn it.
Thus passed classical literature - Greek, Roman, Egyptian. You know, when they say such and such a manuscript is “lost” - really means: destroyed by muslims circa 632 -732 AD - history academia’s loath to acknowledge.