Martin McNamara, «Melchizedek: Gen 14,17-20 in the Targums, in Rabbinic and Early Christian Literature», Vol. 81 (2000) 1-31
The essay is introduced by some words on the nature of the Aramaic translations of Gen 14 used in the study (the Tgs. Onq., Pal. Tgs. as in Tgs. Neof. I, Frg. Tgs., Ps.-J.). Tg. Neof. identifies the Valley of Shaveh (Gen 14,17) as the Valley of the Gardens (pardesaya). The value of Tg. Neof.s evidence here is doubtful. Most Targums retain Melchizedek as a personal name (not so Tg. Ps.-J.). Salem of v. 18 is identified as Jerusalem. Melchizedek is identified as Shem, son of Noah, mainly because of the life-span assigned to Shem in Gen 11. The question of Melchizedeks priesthood in early rabbinic tradition and in the Targums (Tg. Gen 14; Tg Ps. 110) is considered, as is also the use of Jewish targumic-type tradition on Melchizedek in such early Fathers as Jerome, Ephrem, and Theodore of Mopsuestia.
(Panarion haer. 55.6.1; Adv. Haer. 2.1 [Contra Melchizedecianos]) knew of the tradition21. He uses the LXX of Gen 11 to prove that Shem could not possibly have been Melchizedek, which belief he attributes to the Samaritans rather than to the Jews.
In Hebrew Questions on Genesis 14,18-19 (a work completed, as just noted, between late 391 and early 393), Jerome succinctly states the Jewish tradition of his own day on the matter22:
And Melchisedech king of Salem... Because our little book is, in a word, a collection of Hebrew questions or traditions, let us therefore introduce what the Hebrews think about this. They declare that this man is Sem, the son of Noah, and by calculating the years of his life, they show that he lived up to the time of Isaac; and they say that all the first-born sons of Noah were priests before Aaron performed the priestly office. Next, by "king of Salem" is meant king of Jerusalem, which was formerly called Salem.
The computation of the years of Shems life mentioned here by Jerome is referred to again, and spelt out, in his Letter 73.5 to the presbyter Evangelus on Melchisedek (written in 398). Here Jerome says that the Hebrews have a tradition that Melchisedek of Gen 14 was the eldest son of Noah and that at the time of the birth of Abram he (Shem) was three hundred and ninety years old. He goes on to tell us the manner in which they calculate this, giving us from Gen 11 a chart of the sort we find in modern scientific treatments of this question23. The Hebrew computation chart as given by Jerome runs as follows:
Shem, on the second year after the Flood,
when he was a hundred years old, begot Arpachshad
Shem, after the birth of Arpachshad, lived
500 years (in all 600 years) Arpachshad became the father of Shelah after 35 years Shelah became the father of Eber after 30 years
Eber became the father of Peleg after
34 years Peleg became the father of Reu after 30 years Reu became the father of Serug after 32 years Serug became the father of Nahor after 30 years Nahor became the father of Terah after 29 years Terah became the father of Abraham after 70 years