The provinces of the Persian Empire were called satrapi.
Biblical Persia is roughly where the Islamic Republic of Iran is today. However, Biblical Persia was larger than today's Iran, expanding into parts of modern Kuwait, Iraq, Azerbaijan, Afghanistan, and Pakistan.
Persia
There is not a country called Persia at present. Today's Iran was called Persia in ancient times. Now it is 1.68sq km.
The question makes a somewhat-incorrect initial claim. As can be seen in the above map, Iraq and Afghanistan were regions that came under the historic control of Persia on different occasions. However, these regions were never called "Persia". Iraq generally went by the name "Mesopotamia" and Afghanistan had several names, such as North Khorasan, Parthia, Bukhara, etc.The historic country of Persia is properly identified with the modern Islamic Republic of Iran, which is its successor-state (post-revolution).
Persian, also known as Farsi, is an Indo-European language that has its origins in ancient Persia (modern-day Iran). It has evolved over thousands of years and has been influenced by various languages, including Arabic and Turkic languages. It is the official language of Iran and is also spoken in parts of Afghanistan and Tajikistan.
Iran was Persia.
The Republic of Iran.
The Achaemenid Empire pronounced (Hakhamaneshiyan) also known as Persian empire with its continent called Persia is today's Iran, Afghanistan, Tajikistan, Ancient Egypt, some of Pakistan, India, with northern Saudi Arabia, Jordan, Israel, Lebanon, Syria, Libya and Coastal Regions of Iraq. Hope that helps. :)
The Persian Empire stretched from what is today Afghanistan in the east, trough Persia to Asia Minor in the west.
Persia (today known as Iran)
Zoroaster Balkhi was born in city Balkh, Afghanistan, which use to be Persia as well. Today the Dari Zoroasterian language only spoken by Afghans.