Why can Persia and Russia compete for hundreds of years for the Caucasus?

The Caucasus has a superior geographical position.

The Caucasus mountains, rugged roads, and mainly farming are not the places that the plains yearn for. In terms of location, the Caucasus is adjacent to the Caspian Sea in the east and the Black Sea in the west, which is the only land passage between West Asia and Eastern Europe. Geographically, the northern Caucasus is Russia, and the southern Caucasus is Turkey and Iran (called Persia in ancient times), so the reasons in this regard are doomed to numerous disputes here.

in the 6th century BC, the Persian dynasty was a great empire spanning Europe, Asia and Africa, and the mountainous peoples in the Caucasus succumbed to Persia. The Roman empire has not yet expanded to this point, and Persia is the master of the Caucasus. After the internal integration of Rome, the authority of Persia was challenged. As the northern border of Persia, the Caucasus was often contested between Rome and Persia until the 16th century.

With the rise of Russia, Persia was threatened, and the Russians built forts to migrate Slavs. The Russian army came with the immigrants. Persia was extremely angry and launched an attack on Russia. The provincial party Committee was fully prepared and Russia could not resist. After fierce fighting, Russia withdrew from the Caucasus and Persia won a military victory. The Persians were ready to drive Russia back to Eastern Europe, the Mughal dynasty invaded Kandahar, and Persia was forced to make peace with Russia and rush to the south. The initial action suffered heavy losses, and Russia will not let it go. After preparing for the war, it will once again launch revenge against Persia. In 1722, there was civil strife in Persia, and Russia attacked on a large scale. Persia was unable to resist. The two sides signed the famous Treaty of St. Petersburg, and Persia gave Russia the North and South Caucasus.

In the following ten years, Russia was the master of the Caucasus. By 1735, the relationship between Russia and Ottoman Turkey had gradually deteriorated. The northern Caucasus is Russia, the southwest is Ottoman Turkey, and the southeast is Persia. The relationship between Ottoman Turkey and Persia and Russia is not very good. When a crisis broke out in Russia and Turkey, Russia returned the Caucasus to Persia in order to maintain a neutral position between Russia and Turkey. The war between Russia and Turkey ended, and Persia was doomed. In 1796, the Queen of Russia marched into the Caucasus, and Persia was unable to resist. Soon the Queen of Russia died of illness and Russia withdrew.