The War of Lanka by Sahibdin.It depicts monkey army of the protagonist Rama (top left, blue figure) fighting the demon-king of the king of Lanka, Ravana in order to save Rama's kidnapped wife Sita. The painting depicts multiple events in the battle against the three-headed demon general Trisiras, in bottom left - Trisiras is beheaded by the monkey-companion of Rama - Hanuman.
Trishira or Trisiras (Sanskrit: त्रिसिर)ไทย : ตรีเศียร, one having three heads) was a three-headed asura in Ramayana.
Story
He was one of the seven sons of Ravana, and his other brothers were Indrajit, Prahasta, Atikaya, Akshayakumara, Devantaka and Narantaka.
He engaged Rama in a fight and hit him with a number of arrows. At this Rama told that the arrows were nothing but like flowers being showered on his body. Thereafter, a duel ensued, in which Rama killed Trishira.