Abū Zayd ‘Abd ar-Raḥmān ibn Muḥammad ibn Khaldūn al-Ḥaḍramī; may Allah have mercy upon him was a famous historian who died a little over 500 years quoted a reference from Al Ghani. In his reference he substituted the words Asmar Shadeed As Sumurah with Adam Shadeed Al Udmah to explain that it means jet black.
This is is clear proof to show how the Arabs understood what Asmar meant in his time. This also proves how intense Asmar can mean jet black and that Asmar on its own could never mean tanned, the way many try to
”The owner Al Ghani (the book) mentioned them (The children of Malik) and he said that verily they were only called The Green ones because of the blackness and the Arabs named jet black, green he said Malik was Shadeed As Sumurah and his children resembled him”
ذكرهم صاحب الأغاني وقال انما سموا الخضر لسوادهم والعرب تسمى الأسود أخضر قال وكان مالك شديد السمرة فأشبهه ولده
Kitaab Al Al Ghaani
”He said, The Children of Malik Ibn Turayf were named Al Khudra (The Green) because of the blackness and Malik was Adam Shadeed Al Udmah and his sons came out to him(born) so it was said to them( ie they were named) the Green and the Arabs named Jet black (things, people), Green”
قال وسمي ولد مالك بن طريف الخضر لسوادهم وكان مالك شديد الأدمة وخرج ولده إليه فقيل لهم الخضر والعرب تسمي الأسود الأخضر