To read up on is to study a subject by reading about it. Read up on the history first.
It is done before rather than during, which is what separates it from looking something up. To read up on a place before going doubles what you actually see there.
1phraseread up onTo study a subject by reading about it.
“He would read up on every country before he set foot in it.”
read up on is a phrase.
Practised in Phrasal Verbs