Instability in Basra helped foster economic prosperity in Kuwait. In the late 18th century, Kuwait was a haven for Basra merchants fleeing Ottoman persecution. Kuwait was the center of boat building in the Persian Gulf, its ships renowned throughout the Indian Ocean. Kuwaitis also developed a reputation as the best sailors in the Persian Gulf. In the 19th century, Kuwait became significant in the horse trade, with regular shipments in sailing vessels. In the mid 19th century, it was estimated that Kuwait exported an average of 800 horses to India annually.