Dec 3 (Reuters) - Morocco's late King Hassan told fellow north African leaders in 1990: "Our aim is to turn the Arab Maghreb into one country with one passport... one identity and a single currency."
But each step towards unity has proved transient: the Morocco-Algeria frontier remains closed as tensions simmer over Morocco's presence in the disputed Western Sahara.
Following are key events in relations between regional rivals Morocco and Algeria that affected their common border.
1844 - A series of battles between French and Moroccan troops lead to the Treaty of Tangier in which Morocco recognises Algeria as part of the French empire with a defined frontier.
1912 - Morocco becomes a French protectorate under the Treaty of Fez. France shifts border westwards to place more land within its colony Algeria. Morocco regains independence in 1956.
1963 - A two-month conflict breaks out between Morocco and newly independent Algeria after each side accuses the other of a creeping takeover of desert territory along 1,200-km (750 miles) of frontier. The border is closed.
1964 - The Organisation of African Unity steps in to settle the dispute, allowing the border to reopen.
1972 - Algeria and Morocco come to an agreement over their common border but Morocco waits 20 years before ratifying it.
1976 - The border is closed again after Morocco's "Green March" into Spain's former colony Western Sahara sours relations with Algeria, which supports Saharan independence movement Polisario.
1988 - Diplomatic relations between Morocco and Algeria resume and the border reopens. Prospects for regional integration appear to be the brightest in many years.
1994 - Morocco imposes visa restrictions on Algerian nationals after gunmen kill two Spaniards at a Marrakesh hotel. It blames two Moroccan fugitives who had been manipulated in the past by Algerian military security. Algeria shuts the border.
1999 - Ties appear to improve after the death of Morocco's King Hassan but plans to reopen the border are aborted after a deadly attack by the Algerian Armed Islamic Group (GIA). Algeria says the rear bases for the attack were in Morocco.
(Sources: Reuters, University of Oxford's Oriental Institute) (Reporting by Tom Pfeiffer)