The document discusses the rise of trade by sea, starting with the spread of Islam which encouraged networking and trade. Muslims dominated Indian Ocean trade in goods like ivory, pearls, rice and cotton. The Portuguese then gained control over many sea routes between the 15th-16th centuries by occupying ports in India, the Persian Gulf and Sri Lanka. More recently, the 2004 tsunami in Indonesia impacted the spread and practice of Islam there. Piracy has been common in the Indian Ocean for centuries, especially after Western intrusion, and is sometimes seen as a legitimate practice by communities like in Puntland.