The word "ashen" comes from Middle English asshen, meaning "made of ashwood", and a derivative of the Old English word  æsċen.   It has two primary etymological paths: one relating to the ash tree and another, more common one, relating to the pale color of ashes from a fire. The second meaning, to be pale or "lifeless," emerged as the pale color of ashes became associated with shock or fear. 

The word "ashen" first appeared in English during the Middle English period, with the Oxford English Dictionary (OED) citing its earliest evidence before 1400 for the meaning "made of ash wood". The adjective "ashen" in the sense of "ash-colored" or "deadly pale" first appeared in the early 1800s, with the OED noting its earliest use in 1808.  Others cite 1807 instead. 

Examples of "ashen" used in English: 
"He was taller than all his men with long ashen hair and piercing gray eyes." 
"It was the color of an ashen dove and reached her ankles." 
"He was ashen and trembling in fear." 
"He fell back, shocked, his face ashen."