Flags of the world

A cover from United Nations with random flags of the world ! 

Brunei 

The flag of Brunei has a centered crest of Brunei on a yellow field cut by black and whitediagonal stripes (parallelograms at an angle). The yellow field represents the sultan of Brunei. The red crest consists of a crescent facing upwards, joined with a parasol, with hands on the sides. Black and white stripes run across the flag. In Southeast Asia, yellow is traditionally the color of royalty, The crescent symbolizes Islam, the parasol symbolizes monarchy, and the hands at the side symbolize the benevolence of the government. The black and white stripes represent Brunei's chief ministers. On the crescent is the national motto in Arabic: “Always render service with God's guidance” (الدائمون المحسنون بالهدى). Below this is a banner inscribed with Brunei Darussalam, which means ‘Brunei, the Abode of Peace’ (بروني دارالسلام‎)

Saint Kitts and Nevis 

The flag of Saint Kitts and Nevis consists of a yellow-edged black band containing two white stars that divides diagonally from the lower hoist-side corner, with a green upper triangle and red lower triangle. A national competition was held in the early 1980s to choose a new flag. The winning design by student Edrice Lewis was one of 258 entries.^[4] It was first hoisted one minute after midnight on 19 September 1983, the day Saint Kitts and Nevis became an independent country.

The green alludes to the country's fertile land, while the red evokes the fight for freedom against slavery and colonialism. The yellow stripes represent the sunshine the islands enjoy all year round, and the black epitomises the people's African origins. The two stars on the black band symbolise Saint Christopher and Nevis — the two islands that make up the federation—as well as "hope and liberty."

Syrian Arab Republic 

The flag of the Syrian Arab Republic consists of three colours: red, white and black, with two green stars, of five angles each.

 The current flag was first adopted in 1958 to represent Syria as part of the United Arab Republic, and was used until 1961. It was readopted in 1980. Since its first adoption, variations of the red-white-black flag have been used in various Arab Unions of Syria with Egypt, Libya, Sudan, Yemen and Iraq. Although Syria is not part of any Arab state union, the flag of the United Arab Republic was readopted to show Syria's commitment to Arab unity.^[3]The usage of the flag has become disputed because it is often associated with the Ba'ath Party and has come to represent parties loyal to Bashar al-Assad's government in the Syrian civil war.

The flag used by the opposition - Independence flag. 

Originally in 1932 with 1:2 aspect ratio, was readopted in 1961. Adopted with 2:3 aspect ratio in 2012 by opposition government-in-exile. 

Democratic Kampuchea 

The flag of Democratic Kampuchea consisted of the golden Angkor Wat in the red background. It was adopted on 5 January 1976 during Khmer Rouge rule under Cambodia.

Although the flag of the People's Republic of Kampuchea became the official flag within Cambodia after the ousting of the Khmer Rouge government, the flag of Democratic Kampuchea would still be used by the Coalition Government of Democratic Kampuchea and in the United Nations. Most states kept diplomatic ties with the Coalition Government of Democratic Kampuchea as the People's Republic of Kampuchea failed to gain widespread international recognition.

The flag of the People’s Republic Of Kampuchea. 

Though this is the flag since 1993 , the UN recognises the older flag of Democratic Republic Of Kampuchea. 

Rwanda 

Rwanda's previous flag was a red-yellow-green tricolour with a large black letter "R" (to distinguish it from the otherwise identical Flag of Guinea). Derived from the flag of Ethiopia, the colours green, yellow, and red represented peace; the nation's hope for its development; and the people. The colours were associated with Pan-African colours. The flag was changed because it became associated with the brutality of the 1994 genocide. 
The Rwandan genocide, also known as the genocide against the Tutsi, was a mass slaughter of Tutsi in Rwanda during the Rwandan Civil War, which had started in 1990. 

The present flag is a different one adopted in 1994 ( though I do not know why the UN still recognises the old flag ) 

A beautiful cover with atleast 3 stamps with flags that have a troubled history ! 

It is also interesting that the cover has two different date cancellations ! The UN covers always has some confusing cancellations on them :)