Final answer:
Malay communities historically influenced the Indian Ocean basin, including regions like the Malacca Sultanate around the Malaccan Straits and trade-based societies in Southeast Asia and East Africa.
Step-by-step explanation:
The Malay communities were historically situated around the Indian Ocean basin, particularly influencing areas like the Malacca Sultanate, which controlled the vital trading route of the Malaccan Straits between the Indian Ocean and the South China Sea. This area, including parts of the Indonesian island of Sumatra and the southern part of the Malay Peninsula, was critical for trade between India, Southeast Asia, and China.
Southeast Asia itself is located between the Indian Ocean to the west and the Pacific Ocean to the east, where various seas, bays, straits, and gulfs contribute to its complex maritime boundaries. Additionally, trade-based societies developed around the Indian Ocean basin, including East Africa, which became a key center of Indian Ocean trade by the twelfth century.