Why does the word "al-Ahmar" appear in the name of ibn al-Ahmar?

Question

Muhammad I of Granada, the founder the last Spanish Muslim kingdom, was also known by the name "Ibn al-Ahmar" ("son of al-Ahmar") The dynasty he founded, the Nasrid dynasty, was also known as "Banu al-Ahmar" ("children of al-Ahmar").

It seems that ''ahmar'' simply means "red" in Arabic. How did Muhammad I and the dynasty come to be associated with these names?

Answer 1

Muhammad ibn Yusuf ibn Nasr (1195–1273) is also known as 'al-Ahmar' because of his clan name, Banu al-Ahmar. Hence, the Nasrid dynasty is also referred to as Banu Nasr or Banu al-Ahmar.

You can see this here:

• The Spread of Islam Throughout the World, edited by Idris El Hareir, Ravane Mbaye, and
• Histoire des Benou’l-Ahmar : rois de Grenade, a 1899 French translation by Maurice Gaudefroy-Demombynes of ibn Khaldun’s History of the Nasrid Dynasty

Answer 2

The Banū l-Aḥmar have their name quite simply from a real or fictitious ancestor with the name (or nick name) al-Aḥmar “the ruddy one”.