From the 12th century, the Baltic tribes were linked by a common struggle with the Livonian Brothers of the Sword (1202–1237), and later with the Order of Livonia.

In the 13th century, during the war with Livonia, many members of Curonians, Semigalians, Selonians and other tribes from the territory of present-day Latvia moved to Lithuania, strengthened its economic and military potential, and eventually merged into the emerging Lithuanian nation.

During the 13th and 15th centuries, during the beginning of the war between the estates of Livonia and Lithuania, a wide stretch of sparsely inhabited or uninhabited land was formed.

According to the treaty, some areas of present-day southern Latvia belonged to Lithuania; the border was established to the north of the current districts of Rokiškis (Dienvidsusēja), Pasvalys (Nemunėlis to Luopgalė), Pakruojis, Joniškis, Naujoji Akmenė districts (later, the border established in 1529 and coincided in many places with the northern border of Kaunas Governorate; the governorate included Aknīste, Grendza, Nereta, Šķirāni, Ukrai and other Lithuanian or mixed settlements).

During the Livonian War (1558–83), the territory of present-day Latvia north of the Daugava was transferred to Lithuania, it became the Duchy of Livonia (1561–1677), which was an autonomous province of the GDL in 1561–69, later it belonged to the Polish–Lithuanian Commonwealth, and was administered by the Lithuanian and Polish dignitaries.

[1] After the Polish–Swedish War (1600–1629) according to the Truce of Altmark (1629), the Commonwealth retained only southern and eastern parts of present-day Latvia, as the Inflanty Voivodeship and the Duchy of Courland and Semigallia.

After the First World War, when the Baltic countries were creating independent states, on 1919 March 1, the Lithuanian and Latvian governments signed an agreement in Kaunas, and Lithuania granted Latvia a 5 million mark loan, acquired the right to use the port of Liepāja duty-free for the transport of military and commercial cargo for a while, and agreed to fight the Bolsheviks together.

On September 12, 1934, in Geneva, Estonia, Latvia and Lithuania signed the Treaty of Harmony and Cooperation between the States; the political diplomatic union Baltic Entente was formed.

The legal sovereignty of Latvia, Lithuania and Estonia was reminded to the world public by the remaining embassies and the communities of emigrants and war refugees who went to Western countries and fought for the restoration of the independence of the Baltic States.

The struggle for the restoration of the independence of the three republics occupied by the USSR became more organized when the young generation of war refugees grew up.

Due to the efforts of the organizations founded by it (American White Freedom League, United American White National Committee, World White Union and others) in 1982-91 in the United States of America and other countries, the Day of White Freedom was celebrated on a national scale, the Baltic Peace and Freedom Cruise was organized in 1985, the 1985 Copenhagen organized Baltic Tribunal; these and many other innovative actions reminded the society of Western countries and international organizations of the case of the freedom of the Baltic countries, and encouraged resistance to the Soviet occupation regime.

From the 20th century In the Soviet Union of the 1960s, demonstrative cooperation of neighboring so-called "unionized republics", so-called "socialist racing", was encouraged (Latvian and Lithuanian cities, districts, companies, farms competed); meetings and connections of intellectuals (e.g. scientists, primarily Latvian and Lithuanian linguists, artists, actors, encyclopedists) contributed to the enrichment of the cultures of both nations.

Relations between the fighters against the Soviet regime were also forged (in 1975 a joint memorandum of the Forty-five Baltic States was signed, other statements).

[6][7] Lithuania's growing economy, especially in industries like retail, manufacturing, and technology, has begun offering attractive job prospects which has led to an increasing number of Latvian citizens moving to work in Lithuania due to Lithuanian employers offering higher salaries and better benefits compared to similar jobs in Latvia.