Early Georgian States of Colchis and Iberia.

A second Georgian tribal union emerged in the 13th century BC on the Black Sea coast under the Kingdom of Colchis in western Georgia.

The Kingdom of Kartli (known as Iberia in the Greek-Roman literature) was founded around 300 BC by Parnavaz I, the first ruler of the Parnavazid dynasty.
Between 653 and 333 BC, both Colchis and Iberia survived successive invasions by the Median Empire, and later the Persian Empire. At the end of the 4th century BC southern Iberia witnessed the invading armies of Alexander the Great, who established a vast Greco-Macedonian empire to the south of the Caucasus.

Roman Empire Kingdom of Lazica

This close association with Armenia brought upon the country an invasion (65 BC) by the Roman general Pompey, who was then at war with Mithradates VI of Pontus, and Armenia; but Rome did not establish her power permanently over Iberia

The former Kingdom of Colchis became the Roman province of Lazicum ruled by Roman legati. The following 600 years of Georgian history were marked by struggle between Rome and Persia (Iran) including Parthians and Sassanids who were fighting long wars against each other for the domination in the Middle East including Syria, Mesopotamia, Armenia, Albania, and Iberia.

Christianity as a State Religion since 337 AD.

King Mirian III established Christianity in Georgia as the official state religion in 337The eastern Georgian Kingdom of Iberia became one of the first states in the world to convert to Christianity in 327 AD, when the King of Iberia Mirian III established it as the official state religion. This adoption of Christianity tied the kingdom to the Byzantine Empire, which exerted strong cultural influence over it. During the 4th and most of the 5th centuries, Iberia (known also as the Kingdom of Kartli) was under Persian control. The Kingdom was abolished and the country was ruled by the governors appointed by the Shahs. At the end of the 5th century though, Prince Vakhtang I Gorgasali orchestrated an anti-Persian uprising and restored Iberian statehood, proclaiming himself the King

King of Georgia David the Builder 

Kingdom of Georgia during King David the Builder in 1124.The struggle against the Seljuq invaders in Georgia was led by the young King David IV of the Bagrationi royal family, who inherited the throne in 1089 at the age of 16 after the abdication of his father George II Bagrationi. Soon after coming to power, David created the regular army and peasant militia in order to be able to resist Seljuq colonization of his country.
 Flag of Georgia during the reign of David the Builder
The Georgian Royal army also welcomed mercenaries from Germany, Italy, and Scandinavia (all those westerners were defined in Georgia as the Franks) as well as from Kievan Rus.

Queen Tamar of Georgia.

The reign of Queen Tamar represented the peak of Georgia s might in the whole history of the nation.
The temporary fall of the Byzantine Empire in 1204 to the Crusaders left Georgia and Bulgarian Empire as the strongest Christian states in the whole East Mediterranean area.
The period between the early 12th and the early 13th centuries, and especially the era of Tamar the Great, can truly be considered as the golden age of Georgia. Besides the political and military achievements, it was marked by the development of Georgian culture, including architecture, literature, philosophy and sciences.

Mongol invasion 

Mongol invasion and decline of the Georgian KingdomIn the 1220s, the South Caucasus and Asia Minor faced the invasion of the Mongols.
In 1243, Queen Rusudan of Georgia signed a peace treaty with the Mongols in accordance with which Georgia lost her client-states and agreed to pay tribute to the Mongols
The period between 1259 and 1330 was marked by the struggle of the Georgians against the Mongol Ilkhanate for full independence. In 1386–1403, the Kingdom of Georgia faced eight Turco-Mongolic invasions under the leadership of Tamerlane. Except in Abkhazia and Svaneti, the invasions devastated Georgias economy, population, and urban centers.

Fall of Constantinople and isolation of Georgia.

In 15th century the whole area changed dramatically in all possible aspects: linguistic, cultural, political, etc. During that period the Kingdom of Georgia turned into an isolated, fractured Christian enclave, a relic of the faded East Roman epoch surrounded by Muslim, predominantly Turco-Iranian-Arabic world.

The fall of Constantinople to the Ottoman Turks in 1453 sealed the Black Sea and cut the remnants of Christian states of the area from Europe and the rest of the Christian world. Georgia remained connected to the West through contact with the Genoese colonies of the Crimea.

Georgia,Russia, Catharina the Great King Erekle II

The emergence of a third imperial power to the north, Christian Russia, made the latter an increasingly tempting choice.King Erekle II Erekle II, king of Kartli-Kakheti from 1762 to 1798, turned towards Russia for protection against Ottoman and Persian attacks. The Russian empress Catherine the Great was keen to have the Georgians as allies in her wars against the Turks, but sent only meagre forces to help them In 1783 Erekle signed the Treaty of Georgievsk with Russia. 

On January 8, 1801, Tsar Paul I of Russia signed a decree on the incorporation of Georgia (Kingdom of Kartli-Kakheti) within the Russian EmpireA part of the Georgian nobility did not accept the decree until April 1802 when General Knorring compassed the nobility in Tbilisis Sioni Cathedral and forced them to take an oath on the imperial crown of Russia. Those who disagreed were arrested temporarily. Georgia was reunified for the first time in centuries but had lost its independence. The 11th Red Army enters Tbilisi. 25 February 1921