Pakistan view

However, some writers believe that when Mughal prince Dara-e-Azam reached a certain place on the river bank after winning many battles, he fixed his flag at that place and called it Ja-e-Alam (Persian: جا علم‎, lit. 'Place of the Flag'). As time passed, the name Ja-e-Alam became Jhelum in its modern form.
The river Jhelum is called Vitastā in the Rigveda and Hydaspes (Greek: Υδάσπης) by the ancient Greeks. The Vitastā (Sanskrit: वितस्ता, fem., also, Vetastā) is mentioned as one of the major rivers by the holy scriptures — the Rigveda. It has been speculated that the Vitastā must have been one of the seven rivers (sapta-sindhu) mentioned so many times in the Rigveda. The name survives in the Kashmiri name for this river as Vyeth. According to the major religious work Srimad Bhagavatam, the Vitastā is one of the many transcendental rivers flowing through land of Bharata, or ancient India.
Anjum Sultan Shahbaz, a Pakistani author, recorded some stories of the name Jhelum in his book Tareekh-e-Jhelum as:[6]

Many writers have different opinions about the name of Jhelum. One suggestion is that in ancient days Jhelumabad was known as Jalham. The word Jhelum is reportedly derived from the words Jal (pure water) and Ham (snow). The name thus refers to the waters of a river (flowing beside the city) which have their origins in the snow-capped Himalayas.The Jhelum enters Punjab in the Jhelum District. From there, it flows through the plains of Pakistan's Punjab, forming the boundary between the Jech and Sindh Sagar Doabs. It ends 67 Kilometers from Mari Shah Sakhira City in a confluence with the Chenab River at Trimmu in the Jhang District. The Chenab merges with the Sutlej to form the Panjnad River, which joins the Indus River at Mithankot.The river Jhelum rises from Verinag Spring situated at the foot of the Pir Panjal in the southeastern part of the Kashmir Valley. It is joined by its tributaries Lidder River near village Mirgund at Khanabal, river Veshaw at Sangam in Anantnag, and Sind River at Shadipora in Kashmir Valley. It flows through Srinagar and Wular Lake before entering Pakistan through a deep narrow gorge. The Neelum River, the largest tributary of the Jhelum, joins it at Domel Muzaffarabad, as does the next largest, the Kunhar River of Kaghan Valley. It also connects with the rest of Pakistan and Pakistani Kashmir at the Kohala Bridge east of Circle Bakote. It is then joined by the Poonch River, and flows into the Mangla Dam reservoir in the Mirpur District.