Final answer:
The four hymns by Guru Nanak discussing Babar's invasions are known as Babarvani, depicting the atrocities and impact of these invasions in Sikh literature.
Step-by-step explanation:
The four hymns by Guru Nanak that refer to the invasions by Babar are collectively known as Babarvani in Sikh literature. These hymns are a poignant reflection on the brutality and the suffering caused by Babar's invasions in the Punjab region. Guru Nanak, the founder of Sikhism and the first of the Sikh Gurus, used these hymns to describe the atrocities committed by Babar and his men during their conquest. The distress and dismay of the local population during these times of turmoil are vividly captured through these hymns, providing a historical account as well as a moral reflection on the events.