Here is a look at Sinai as Egypt mounted its biggest military assault in the area since 1973 in an attempt to end attacks by Islamic militants.
The Sinai Peninsula was the focus of every military confrontation between Israel and Egypt from 1948 until the Israel/Egypt peace accord in 1979 when Sinai was returned to Egypt. Under the deal, Israel withdrew and limits were set on the forces Egypt could deploy in the area.
Tourism in Sinai has been picking up over the last decade but has been hit intermittently as militant Islamist groups based in the north have gradually extended their reach across its mountainous expanses. They have targeted tourists in the south in 2004, 2005 and 2006 with deadly results and forcing the government to reinforce security there.
Sinai has fallen deeper into lawlessness since an uprising overthrew Egypt's autocratic president Hosni Mubarak in 2011.
Bedouin tribesmen have attacked police stations, blocked access to towns and taken foreign tourists and workers as hostages to show discontent with what they see as their poor treatment by Cairo.
The Bedouin account for the majority of the area's 600,000 population. They are not allowed to own land or serve in the army and say they benefit little from local tourism revenue.
(Reporting by David Cutler, London Editorial Reference Unit)