The people of the Persian Gulf coast differ from those of the interior of the Arabian Peninsula.

Many of the people in the interior are organized in tribes and pursue nomadic lifestyles.

When the desert provides insufficient food for their flocks, the tribes push into the date groves or farmlands of the settled towns.

Centers on the gulf coast are subject to such nomadic incursions, as are the people of Mesopotamia.

As a result, the gulf begins to take on an increasingly Arab character after the second millennium BCE.

Some Arab tribes from the interior leave their flocks and take over the date groves that ring the region's oases, while others take up sailing and begin to take part in the trade and piracy that are the region's economic mainstays.

These nomadic incursions periodically change the ethnic balance and leadership of the gulf coast.