Born in Kabul, Afghanistan, Mangal spent much of his early years in refugee camps in neighbouring Pakistan with his family, fleeing from the Soviet invasion of Afghanistan and the subsequent Civil War that followed the Soviet withdrawal. It was in the camps that Mangal, like many of his teammates, was introduced to cricket. The War in Afghanistan saw the US Army put an end to Taliban rule of Afghanistan in 2001 and soon after Mangal returned to the country. In the aftermath, the Afghanistan national cricket team was founded.
Mangal was spotted by then Afghanistan coach Taj Malik. Mangal’s father tried to stop him playing, citing the sport as not being a living. Malik went to the province of Khost on the Pakistani border to speak to with Mangal's family, telling him: "He will be great". Malik stayed the night pleading with him, and by the morning, convinced him to allow Mangal to play. Mangal made his debut for Afghanistan against Nowshehra in the 2001 Quaid-e-Azam Trophy (Grade II). He made his international debut for Afghanistan against Oman in the 2004 ACC Trophy. During the tournament, Mangal was Afghanistan's leading run scorer with 271 runs. It was the first time the team participated in the competition and they progressed to the quarter-finals where they lost to Kuwait.
He captained Afghanistan in their debut, and his debut first class match in the Intercontinental Cup against a Zimbabwe XI in which Afghanistan drew the match. Mangal has subsequently led Afghanistan to victories over the Netherlands and Ireland in the tournament. Mangal made his maiden first-class fifty against Ireland with a score of 84.
In February 2010, Mangal made his Twenty20 International debut against Ireland, which Afghanistan lost by 5 wickets. Mangal led Afghanistan to victory in the 2010 ICC World Twenty20 Qualifier with figures of 3/23 as Afghanistan defeated Ireland by 8 wickets in the final. Afghanistan's victory qualified them to take part in the 2010 ICC World Twenty20. Following the tournament, Mangal led Afghanistan to an astonishing victory over Canada in the Intercontinental Cup. Set 494 to win, Mangal shared a 163 run partnership with Mohammad Shahzad in which he contributed 70 runs to the partnership as Afghanistan won the match by 6 wickets.
In April 2010, Mangal led the side to victory in the 2010 ACC Trophy Elite, where Afghanistan defeated Nepal in the final by 95 runs, with Mangal himself claiming the winning wicket of Rahul Vishvakarma. He is the best Afganistani player.
He scored his maiden first-class century against Kenya in October 2010, making 168 runs before being run out by Elijah Otieno. His innings, along with the bowling of teammate Hameed Hasan, was instrumental in securing Afghanistan a 167 run victory.
In November 2010 it was announced that all-rounder Mohammad Nabi would captain Afghanistan in the 2010 Asian Games twenty20 tournament in China later that month. The Afghanistan Cricket Board released a statement that "We have played 16 one-day internationals but we could only win nine therefore we thought the burden of captaincy is too heavy on Nawroz and Nabi is the next best choice". After causing an upset by beating Pakistan in the semi-finals of the games, Afghanistan lost the final to Bangladesh and finished with a silver medal.