schau doch z.B. mal in das digitalisierte Meyer-Lexikon von 1888 ff. (http://susi.e-technik.uni-ulm.de:8080/Meyers2/index/index.html).
Dort heißt es:
"Beni Asra, arab. Volksstamm, von welchem die (mehrfach dichterisch verwertete) Sage ging, daß sterben müsse, wer unter ihnen von der Leidenschaft der Liebe erfaßt werde."
Das ist, zugegeben, auch nicht viel mehr als man sowieso aus Heines Gedicht entnehmen kann.
In den Geschichten aus 1001 Nacht kann man ebenfalls von den Asra lesen, hier in englischer Übertragung:
THE LOVERS OF THE BANU OZRAH
There was once, among the Banu Ozrah, a handsome and accomplished
man, who was never a single day out of love, and it chanced that
he became enamoured of a beauty of his own tribe and sent her
many messages; but she ceased not to entreat him with cruelty and
disdain; till, for stress of love and longing and desire and
distraction, he fell sick of a sore sickness and took to his
pillow and murdered sleep. His malady redoubled on him and his
torments increased and he was well nigh dead when his case became
known among the folk and his passion notorious;--And Shahrazad
perceived the dawn of day and ceased to say her permitted say.
When it was the Three Hundred and Eighty-fourth Night,
She said, It hath reached me, O auspicious King, that the man
took to his pillow and murdered sleep. So his case became known
and his passion notorious; and his infirmity grew upon him and
his pains redoubled until he was well nigh dead. His family and
hers were urgent with her to visit him, but she refused, till he
was at the point of death when, being told of this, she relented
towards him and vouchsafed him a visit. As soon as he saw her,
his eyes ran over with tears and he repeated from a broken heart,
"An, by thy life, pass thee my funeral train, *
A bier upborne upon the necks of four,
Wilt thou not follow it, and greet the grave *
Where shall my corpse be graved for evermore?"
Hearing this, she wept with sore weeping and said to him, "By
Allah, I suspected not that passion had come to such a pass with
thee, as to cast thee into the arms of death! Had I wist of
this, I had been favourable to thy wish, and thou shouldst have
had thy will." At this his tears streamed down even as the
clouds rail rain, and he repeated this verse,
"She drew near whenas death was departing us, *
And deigned union grant when 'twas useless all."
Then he groaned one groan and died. So she fell on him, kissing
him and weeping and ceased not weeping until she swooned away;
and when she came to herself, she charged her people to bury her
in his grave and with streaming eyes recited these two couplets,
"We lived on earth a life of fair content; *
And tribe and house and home of us were proud;
But Time in whirling flight departed us, *
To join us now in womb of earth and shroud."
Then she fell again to weeping, nor gave over shedding tears and
lamenting till she fainted away; and she lay three days,
senseless. Then she died and was buried in his grave. This is
one of the strange chances of love.
Hilft das weiter?