Since independence in 1962 it has been plagued by tension between the usually-dominant Tutsi minority and the Hutu majority.
The ethnic violence sparked off in 1994 made Burundi the scene of one of Africa's most intractable conflicts.
10.4m population - similar to Belgium
27,816 sq km area - similar to Haiti
50 years life expectancy for men
50 years life expectancy for women
$900 GDP per capita - similar to Liberia
Pierre Nkurunziza, a former Hutu rebel leader, became the first president to be chosen in democratic elections since the start of Burundi's civil war in 1994.
In 2015 Burundi was plunged into its worst crisis since the end of a civil war in 2005, when Mr Nkurunziza's ultimately successful bid for re-election to a third term sparked protests by opposition supporters who said the move was unconstitutional.
Operating in a turbulent political climate, Burundi's media are subject to self-censorship and occasional government censorship.
In June 2013 President Nkurunziza approved a new media law which critics condemned as an attack on press freedom. The law forbids reporting on matters that could "undermine national security, public order or the economy".
Some key dates in Burundi's history:
1890 - The kingdoms of Urundi and neighbouring Ruanda (Rwanda) incorporated into German East Africa.
1916 - Belgian army occupies the area.
1962 - Urundi is separated from Ruanda-Urundi and becomes independent.
1993 - Ethnic conflict claims some 300,000 lives.
2015 - Unrest sparked by president's plans to stand for third term.

The 16-year-old, who also plays age-grade football for her country, defeated 20-year-old Elspeth Young from Kinross 11-4, 5-11, 11-6, 12-10.
In the men's event Scottish number one Alan Clyne, who has risen to world number 32, beat Douglas Kempsell.
He won 11-5, 11-5, 11-2 to earn his seventh Scottish title.
The 30-year-old from Inverness said: "I felt good going through the rounds, but I knew that Douglas would put up a real fight in the final because we all know he is a battler.
"That was the way that it panned out, but I managed to get on the front foot and take the win.
"I am often playing abroad, so I love getting a chance to play in Scottish tournaments and I am very proud to be national champion for a seventh time."
Adderley, seen as Scottish squash's best prospect, said: "Coming into the event aged 16 as number one seed brought its own pressures.
"But I had played in this event last year for the first time and that helped me with nerves and what to expect out there.
"I played well in my semi-final on Saturday and that left me feeling good about the final.
"We had some really good rallies in the first game, but she then came back in the second. At that point I had to hold my nerve, but I did and got a good start to the third game. I then managed to go on and win and the feeling at the end was amazing."
The Scottish National Squash Championships at Edinburgh Sports Club is part of the Team Scotland Series which brings together 17 Scottish national championship events in 2017 across 12 Commonwealth Games sports.
Burundi, one of the world's poorest nations, is struggling to emerge from a 12-year, ethnic-based civil war.
[NEXT_CONCEPT]
Edinburgh teenager Georgia Adderley won the Scottish women's squash title for the first time at the Senior National Championships on Sunday.