elections. A new constitution was approved via public referendum in April 2003 and came into effect in June 2005. Prehistory Paleolithic Age In 1961, a Danish archaeological expedition carried out on the peninsula uncovered approximately 30,000 stone implements from 122 paleolithic sites. Most of the sites were situated along the coastline, and were divided into four separate cultural groups based on flint typology. Macrolithic tools such as scrapers, arrowheads and hand axes dating to the lower and middle paleolithic periods were among the discoveries. The flooding of the Persian Gulf, which occurred roughly 8,000 years ago, resulted in the displacement of Persian Gulf inhabitants, the formation of the Qatari Peninsula and the occupation of Qatar to capitalize on its coastal resources. From this time onward, Qatar was regularly used as rangeland for nomadic tribes from the Najd and al-Hasa regions in Saudi Arabia, and a number of seasonal encampments were constructed around sources of water. Neolithic period (8000–3800 BC) Al Da'asa, a settlement located on the northeast coast of Qatar, is the most extensive Ubaid site in the country. It was excavated by a Danish team in 1961. The site is theorized to have accommodated a small seasonal encampment, possibly a lodging for a hunting-fishing-gathering group who made recurrent visits. This is evidenced by the discovery of nearly sixty fire pits at the site, which may have been used to cure and dry fish, in addition to flint tools such as scrapers, cutters, blades and arrow heads. Furthermore, many painted Ubaid potsherds and a carnelian bead were found in the fire pits, suggesting overseas connections. In an excavation done in Al Khor in 1977–78, several Ubaid-period graves were uncovered in what is considered the earliest recorded burial site in the country. One grave contained the cremated remains of a young woman with no grave goods. Eight other graves contained grave goods, including beads made of shell, carnelian and obsidian. The obsidian most likely originated from Najran in south west Arabia. 235 Bronze Age (2100–1155 BC) The Qatari Peninsula was close enough to the Dilmun civilization in Bahrain to have felt its influence. Barbar pottery was excavated in two sites by the Qatar Archaeology Project, evidencing the country's involvement in Dilmun's trade network. When the people of Dilmun began engaging in maritime activities around 2100 to 1700 BC, the inhabitants of Qatar started diving for pearls in the Persian Gulf. The