مدراش يالكوت كتب فى القرن الحادى عشر أو الثالث عشر بعد الإسلام بخمس قرون على أقل تقدير
تقول الموسوعة اليهودية عن مدراش يالكوت

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Author and Date.

The author of the Yalḳuṭ can not be determined with certainty. The title-page of the Venice edition ascribes the composition of the work to R. Simeon of Frankfort, "the chief of exegetes" ("rosh ha-darshanim"), and this was accepted by Conforte and Azulai, who called him Simeon Ashkenazi of Frankfort. Rapoport (in "Kerem Ḥemed," vii. 7 et seq.), on the other hand, maintained that R. Simeon (the father of R. Joseph Ḳara), who flourished in the eleventh century, was its author; but this assertion is untenable since the compiler of the Yalḳuṭ used midrashim of a later date. If the Yalḳuṭ was so old, moreover, it would be difficult to explain why no mention of it is made by R. Nathan b. Jehiel, the author of the "'Aruk," or by Rashi. All the proofs advanced by Rapoport have been refuted by Epstein, who inclines to agree with Zunz that the author of the Yalḳuṭ flourished in the early part of the thirteenth century. According to Zunz, the work was written by R. Simeon Ḳara, who lived in southern Germany at that period, and the title "ha-Darshan" was bestowed upon him probably at a later date. It is certain that a manuscript of the Yalḳuṭ, mentioned by Azariah dei Rossi, existed in 1310 (comp. Zunz, "G. V." pp. 295-303); but despite this, there is scarcely any allusion to the work during the fourteenth and fifteenth centuries. This may be ascribed, however, to the unhappy position of the German Jews and to the repeated persecutions of the period; for peace and prosperity were necessary for the copying of so extensive a work, and the Jews of Germany had neither. After the beginning of the fifteenth century, on the other hand, the work must have been disseminated in foreign countries, for it was used by Spanish scholars of the latter half of that century, Isaac Abravanel being the first to mention it (comp. Epstein, l.c. p. 134).
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و ملخص ما سبق
هو أن المؤلف غير معروف على وجه التحديد
فمنهم من اعتبر أنه رابي سيميون و قد عاش فى القرن الحادي عشر
لكن ما ضد تلك الفرضية أن من قام بتجميع المدراش اعتمد على مصادر هجادية و مدراشية أخرى ترجع إلى ما بعد القرن الحادى عشر
و أيضا لو كان المدراش يرجع للقرن الحادى عشر فما سر عدم وجود أى إشارة له من رابي ناثان و فى تفسير راشي ؟
و منهم من رأى أن المدراش تم تأليفه فى القرن الثالث عشر بواسطة رابي سيميون كارا و كان يعيش فى جنوب ألمانيا
لكن المؤكد أن مخطوطة مدراش يالكوت كانت موجودة سنة 1310
و لم يكن المدراش معروفا فى القرنين الرابع و الخامس عشر ربما بسبب الظروف السياسية لليهود و اضطهادهم
لكن فى القرن الخامس عشر كان للمدراش شهرة كبيرة

و أما مدراش جنسيز رباه فسنتكلم عنه بشئ من التفصيل إن شاء الله تعالى عند قصة إبراهيم عليه السلام