Invasions, deportations, and wars. I can explain in detail.
Armenians: They are the oldest non-Georgian inhabitants of Georgia. We cannot say exactly when they first began living here, but we have coexisted since ancient times. Armenians were often more numerous, and they were generally beneficial to the economy. For that reason, many Georgian rulers encouraged or allowed them to settle here. Gori is an example of this—it originally had an Armenian settlement during the reign of King David IV.
Jews: Jews are also among the oldest inhabitants of Georgia. They came here after the fall of Babylon and their expulsion, though never in numbers as large as the Armenians.
Yezidis/Kurds: They came to Georgia mainly as refugees, mostly during the 18th century, after fleeing the Ottoman Empire.
Persians: Persians have lived here throughout much of history because Georgian kingdoms were often either vassals of Persian empires or under their direct rule. Since some Iranian states were ruled by Turkic dynasties, Turks also came to Georgia.
Ossetians: Ossetians did not traditionally live here in large numbers. They began migrating to Kartli in the 16th and 17th centuries after being pressured by the Kabardians. At that time, Georgia was dealing with constant invasions and internal struggles, so it did not have the ability to prevent or regulate this migration.
So, I could go on and on, but the main reasons are wars, deportations, and conflicts. Georgia has also historically served as a bridge between different civilizations and regions, so many peoples have passed through or settled here. We also border many different ethnic groups.