When you check Wikipedia on Sufism, it reverts back with the following definition:
Sufism is a concept in Islam, defined by scholars as the inner, mystical dimension of Islam; others contend that it is a perennial philosophy of existence that pre-dates religion, the expression of which flowered within the Islamic religion.
Rumi is a great Sufi poet and his poems offer deep wisdom.
The following Sufi story (Source: Book " The Language of God: A Scientist presents Evidence for the Belief ” by Francis Collins) always puts me on modesty: