Information:  - Babylon (or ; Aramaic: , "Babel", , "Bavel", , "Bbil") was a major city of ancient Mesopotamia in the fertile plain between the Tigris and Euphrates rivers. The city was built upon the Euphrates and divided in equal parts along its left and right banks, with steep embankments to contain the river's seasonal floods. Babylon was originally a small Semitic Akkadian city dating from the period of the Akkadian Empire c. 2300 BC.  - China, officially the People's Republic of China (PRC), is a unitary sovereign state in East Asia. With a population of over 1.381 billion, it is the world's most populous country. The state is governed by the Communist Party of China, and its capital is Beijing. It exercises jurisdiction over 22 provinces, five autonomous regions, four direct-controlled municipalities (Beijing, Tianjin, Shanghai, and Chongqing), and two mostly self-governing special administrative regions (Hong Kong and Macau), and claims sovereignty over Taiwan. The country's major urban areas include Shanghai, Guangzhou, Beijing, Chongqing, Shenzhen, Tianjin and Hong Kong. China is a great power and a major regional power within Asia, and has been characterized as a potential superpower.  - The Parthian Empire (247 BC  224 AD), also known as the Arsacid Empire, was a major Iranian political and cultural power in ancient Iran and Iraq. Its latter name comes from Arsaces I of Parthia who, as leader of the Parni tribe, founded it in the mid-3rd century BC when he conquered the region of Parthia in Iran's northeast, then a satrapy (province) in rebellion against the Seleucid Empire. Mithridates I of Parthia (r. "c". 171138 BC) greatly expanded the empire by seizing Media and Mesopotamia from the Seleucids. At its height, the Parthian Empire stretched from the northern reaches of the Euphrates, in what is now central-eastern Turkey, to eastern Iran. The empire, located on the Silk Road trade route between the Roman Empire in the Mediterranean Basin and the Han Empire of China, became a center of trade and commerce.  - The Seleucid Empire ("Basileía tn Seleukidn") was a Hellenistic state ruled by the Seleucid dynasty, which existed from 312 BC to 63 BC; it was founded by Seleucus I Nicator following the division of the Macedonian empire vastly expanded by Alexander the Great. Seleucus received Babylonia and, from there, expanded his dominions to include much of Alexander's near eastern territories. At the height of its power, it included central Anatolia, Persia, the Levant, Mesopotamia, and what is now Kuwait, Afghanistan, and parts of Pakistan and Turkmenistan.  - Mithridates or Mithradates I (Parthian: "Mihrdat", , "Mehrdd"), (ca. 195 BC  132 BC) was king of the Parthian Empire from 165 BC to 132 BC, succeeding his brother Phraates I. His father was King Phriapatius of Parthia, who died ca. 176 BC). Mithridates I made Parthia into a major political power by expanding the empire to the east, south, and west. During his reign the Parthians took Herat (in 167 BC), Babylonia (in 144 BC), Media (in 141 BC) and Persia (in 139 BC). Because of his many conquests and religious tolerance, he has been compared to other Iranian kings such Cyrus the Great (d. 530 BC), founder of the Achaemenid Empire.  - The Roman Empire (Koine and Medieval Greek:   , tr. ) was the post-Roman Republic period of the ancient Roman civilization, characterized by government headed by emperors and large territorial holdings around the Mediterranean Sea in Europe, Africa and Asia. The city of Rome was the largest city in the world BC AD, with Constantinople (New Rome) becoming the largest around 500 AD, and the Empire's populace grew to an estimated 50 to 90 million inhabitants (roughly 20% of the world's population at the time). The 500-year-old republic which preceded it was severely destabilized in a series of civil wars and political conflict, during which Julius Caesar was appointed as perpetual dictator and then assassinated in 44 BC. Civil wars and executions continued, culminating in the victory of Octavian, Caesar's adopted son, over Mark Antony and Cleopatra at the Battle of Actium in 31 BC and the annexation of Egypt. Octavian's power was then unassailable and in 27 BC the Roman Senate formally granted him overarching power and the new title "Augustus", effectively marking the end of the Roman Republic.  - Phraates II ( Persian :    ) , was king of the Parthian Empire from 132 BC to 126 BC. He is mostly known to reconquer Babylon . He was the son of Mithridates I ( 171 -- 126 BC ) . Because he was still very young when he came to the throne , his mother Ri - ' nu ruled on his behalf at first .  - The Euphrates (Sumerian: : "Buranuna", : "Purattu", : "al-Furt", : "Prt", : "Yeprat", : "Perat", ) is the longest and one of the most historically important rivers of Western Asia. Together with the Tigris, it is one of the two defining rivers of Mesopotamia. Originating in eastern Turkey, the Euphrates flows through Syria and Iraq to join the Tigris in the Shatt al-Arab, which empties into the Persian Gulf.  - Iran (, also , ; ' ), also known as Persia, officially the Islamic Republic of Iran (' ), is a sovereign state in Western Asia. It is bordered to the northwest by Armenia, the "de facto" Nagorno-Karabakh Republic, and Azerbaijan; to the north by the Caspian Sea; to the northeast by Turkmenistan; to the east by Afghanistan and Pakistan; to the south by the Persian Gulf and the Gulf of Oman; and to the west by Turkey and Iraq. Comprising a land area of , it is the second-largest country in the Middle East and the 18th-largest in the world. With 82.8 million inhabitants, Iran is the world's 17th-most-populous country. It is the only country with both a Caspian Sea and an Indian Ocean coastline. The country's central location in Eurasia and Western Asia, and its proximity to the Strait of Hormuz, make it of great geostrategic importance. Tehran is the country's capital and largest city, as well as its leading economic center.  - The Tigris is the eastern member of the two great rivers that define Mesopotamia, the other being the Euphrates. The river flows south from the mountains of southeastern Turkey through Iraq and empties itself into the Persian Gulf.    What is the relationship between 'phraates ii' and 'mithridates i of parthia'?
The answer to this question is:
father