In the eighteenth year of the reign of Ivan Alexander - i. e. 1349 - he and his troops faced a 20,000-strong Ottoman army under the command of Murad I's elder brother Süleyman.

The fierce battle between Bulgarians and Turks took place in the area around Sofia.

That shows that the battle claims many casualties from both sides and Ivan Asen perished fighting bravely for his country.

[2] It seems that despite the great losses the Bulgarians had repulsed the enemy as the next recorded Ottoman invasion occurred 6 years later, in 1355, when in the battle of Ihtiman the Ottoman Turks killed Asen's eldest brother, Michael Asen.

Ivan Asen IV married a Wallachian princess from the Basarab dynasty and had two daughters.