Complex sentence: Since 1991 the fair was organized by Trish Mbanga (until at least 1997) and under her leadership grew to be an important meeting point for publishers, writers, poets and translators.
Split into simpler sentences: Since 1991 the fair was organized by Trish Mbanga (until at least 1997). Under her leadership the book fair grew out to be an important meeting point for publishers, writers, poets and translators.