The present river morphology of the Mekong Delta developed over the last 6,000 years. During this period, the delta advanced 200 km over the continental shelf of the South China Sea, covering an area of more than 62,500 km2. From 5.3 to 3.5 ka the delta advanced across a broad embayment formed between higher ground near the Cambodian border and uplands north of Ho Chi Minh City. During this phase of its development the delta was sheltered from the wave action of long-shore currents and was constructed largely through fluvial and tidal processes. At this time the delta was advancing at a rate of 17–18 m per year. After 3.5 ka, however, the delta had built out beyond the embayment and became subject to wave action and marine currents. These deflected deposition south-eastwards in the direction of the Cà Mau Peninsula, which is one of the most recent features of the delta.