Urouge is a pirate who hails from a sky island and is the captain of the Fallen Monk Pirates. He is one of twelve pirates who are referred to as "The Worst Generation"
Urouge's name was derived from that of real-life 16th century Barbary pirate, Oruç Reis.
And his epithet "mad monk" is derived from
the guy even has a movie after him
The Mad Monk -Ji Gong (濟公, pinyin: Jì Gōng; The Mad Monk in English) is a 1993 Hong Kong comedy film
Birka was a sky island far to the southeast from Skypiea.It is the birthplace of Enel and his followers.
Enough of info now lets jump into theory ,6yrs pior to current storyline Enel and his followers destroyed the homeland called brika
birka name is derived from ancient city of moon and there were 3 races of winged people
after their arrival the 1st island they inhabited was brika sky island ,At some point in history, the three races became separated from each other and fell into the individual races. The Birkans settled on a Sky Island apparently named after their former home, Birka. They also appeared to "forget" their origins, although the moon, known to them as the "Fairy Vearth" remained a folk tale amongst their people, believing it to be a place of dreams.
i believe that Urogue was the God of brika ,now hold your horses God doesnt mean that he was almighty and powerful as we have seen gan fall God of skypeia ,a old man with no powers
why urouge was from brika ?
1.look at his wings its similar ones enel's priests had
He dresses in similar robes to Divine Soldiers underneath the khaki robes he wears (which is also worn by the rest of his crew), which includes the white full-bodied garment with severed sleeves
2. their name Fallen Monk Pirates
enel tried to destroy the skypeia as people living in the sky is unnatural, so as God it is his job to keep the natural order.so we can assume he destroyed his homeland for same reasons ,and monks who survived the fall or escaped the island are urouge and his followers hence named fallen monks pirates
notice as divine solders and maidens with him and they follow him as there leader same as gan fall
3.his fear for lighting -After the war at Marineford, he and his crew go to the New World. They followed their Log Pose to a dark and stormy island that was spewing lightning, with no way to have a ship docking there
the raijin island
4. as captain of white berets said some fought enel and and his followers but were unsuccessful they maybe fallen monk pirates
scenario 2 :
this is short one ,but one of possibility inspired by destruction real brika
urouge and his followers returned home to only to find there home wiped out without a trace and hence left for blue sea ,i find this unlikely but worthy enough to mention as inspired by real events is one of oda's thing
urouge's future role
i believe that winged races (shandia,skypeia and brika) were once allied with ancient kingdom
for now luffy saved both shandia and skypeians from enel and his follower and took payback for brika ,which urouge doesnt know, its very similar to laboon and brook, luffy stopped laboon from damaging himself later, brook was thankful for that and at some point of time urouge will ally himself with luffy similar to shandia and skypeia people
side note: urouge might meet strawhats at elbaf as the land rule by God theme is similar to skypeia