The phrase "important precursor" refers to something that comes before and is necessary for the development or occurrence of something else. Full definition
Considered shocking and even characterized as a cheap swindle when they were first exhibited publicly in 1953, the White Paintings have gradually secured a place in art history as important precursors of Minimalism and Conceptualism. (sfmoma.org)
Uhm — it's important for liver detoxification, it's important precursor for glutathione, right? (justinhealth.com)
They serve as important precursors to her Infinity Mirror Rooms. (ago.ca)