Contain:

Persian is the official language of Iran, Afghanistan, and Tajikistan.

It is also spoken by many people in Pakistan, Uzbekistan, Azerbaijan, immigrants from central Asia in Russia and in order neighbouring  countries.

Persian was also taught as a second language in schools in Pakistan until 2006.in the past many of these places were parts of the Persian Empire.  

Persian has many dialects. The Persian language is officially called Farsi in Iran, Dari and Farsi in Afghanistan and Tajik in Tajikistan, the literary language of each of these countries is a little different. But people from each country can understand each other when they have a conversation it has taken on many French words in Iran and many Russian words in Tajikistan.

Persian is a very old language and linguists have names for three different versions of Persian that  were used in three different  times. Old Persian was spoken in the first Persian empire. Under the Achaemenid  kings, including Cyrus and Darius the Great. This first empire started in the 6^th century BC and continued until Alexander the Great conquered it. A second Persian empire, the Sassanian kings , ruled from the 2^nd century AD until the Muslim conquest of Iran by the Arabs in the 7^th century and middle Persian was spoken by them.

And this question is going to be asked that what is the difference between Persian and Farsi ?!

Dari or Afghan Persian is used in Afghanistan. Tajiki or Tajik Persian is used in Tajikistan, Uzbekistan and Russia. In Iran the Persian language is also known as Farsi. It is known to the English speaking world. And the language spoken by Afghan tajik is the same, if not, very close to the Persian spoken in Iran.

In all over the world and between all countries, Persian language is one of the most beautiful language. And foreigners would like to learn this perfect language.

And from west to east, the nations will be different:

Kurds ( Turkey, Syria, Iraq, Iran)

Azeris ( Azerbaijan, Armenia, Iran)

Persians ( Iran, Afghanistan)

Turkmens ( Iran, Turkminstan)

Pashtuns ( Iran,Pakistan, Afghanistan)

Tajiks ( Tajikistan, Uzbekistan)