With reference to Indian history, consider the following statements: 1. The first Mongol invasion of India happened during the reign of Jalal-ud-din Khalji. 2. During the reign of Ala-ud-din Khalji, one Mongol assault marched up to Delhi and besieged the city. 3. Muhammad-bin-Tughlaq temporarily lost portions of north-west of his kingdom to Mongols. Which of the statements given above is/are correct?

Let's analyze the statements regarding Mongol invasions in Indian history:

1. The first Mongol invasion of India happened during the reign of Jalal-ud-din Khalji: While the Mongols, under Genghis Khan, first reached the Indus frontier in 1221 during Iltutmish's reign, the first significant incursions into the Delhi Sultanate's core territory and concerted attempts at conquest began later. The first major and sustained Mongol invasion that reached the vicinity of Delhi occurred in 1292 under Abdullah, a grandson of Hulegu, during the reign of Jalal-ud-din Khalji. Thus, in the context of direct invasions threatening the Sultanate, this statement is considered correct.
2. During the reign of Ala-ud-din Khalji, one Mongol assault marched up to Delhi and besieged the city: This statement is correct. Ala-ud-din Khalji faced numerous severe Mongol invasions. The most famous was in 1303, when Targhi's Mongol army marched up to Delhi and besieged the city, forcing Ala-ud-din to take refuge in the Siri fort and reorganize his defenses.
3. Muhammad-bin-Tughlaq temporarily lost portions of north-west of his kingdom to Mongols: This statement is incorrect. Muhammad-bin-Tughlaq did face a major Mongol invasion led by Tarmashirin around 1327-29. However, he managed to repel the invasion, either through force or by bribing the Mongols, and did not lose permanent or even temporary portions of his kingdom to them. His policies, like shifting the capital, were partly influenced by the Mongol threat, but he did not lose territory. Therefore, statements 1 and 2 are correct.