Original: It was the birthplace of St. Francis, who founded the Franciscan religious order in the town in 1208, and St. Clare (Chiara d'Offreducci), the founder of the Poor Sisters, which later became the Order of Poor Clares after her death.
Simplified: St Francis is most famous for founding (beginning) a religious order of Friars (Brothers) called the Franciscan, in 1208. One of St Francis' followers, St. Clare was also born in Assisi and founded an order of religious women called the Poor Clares.