Yemen is in the Arab World, southern half of the Arabian Peninsula, bordering the Arabian Sea, Gulf of Aden, and Red Sea. It lies south of Saudi Arabia and west of Oman.A number of islands belong to Yemen, many of which are volcanic.Jabal-al-tair had a volcanic deruption in 2007 and in 1883.It is the World's 49th largest country in the world. It is equal in size with Thailand and larger in size than Californea.It is divided geographically into four main regions: the coatal plains in the west , the western highlands, the eastern highlands, and the Rub al Khali in the east.The Tihamah (hot lands or hot earth) form a very arid and flat coastal plain.It is a very soothing ground for malaria mosquitos.The evaporation in Tihama is so great that streams from the highlands never reach the sea, but they do contribute to to extensive ground water reserves. Today, these are heavily exploited for agricultural use.Near the village of Madarabout 48km north of Sanaa dinosaur footprints were seen, indicating that the area was once a muddy flat.. 