the jewish website, jewfaq.org, says:

the minimum age for marriage under jewish law is 13 for boys, 12 for girls; however, the kiddushin [betrothal] can take place before that, and often did in medieval times.

(jewfaq.org, http://www.jewfaq.org/marriage.htm)

the age of twelve approximates the commencement of puberty. according to jewish law, marriage at this age is not just allowed, but rather it is actively encouraged and fathers are advised to quickly wed their pubescent daughters. we read:

one passage that would echo long and loud for ashkenazic jews throughout the middle ages held that a man who marries off his sons and daughters near the period of puberty (samukh le-firkan) will receive the scriptural blessing: “you shall know that your tent is in peace” (job 5:24), evidently understood to mean that if one’s children were married, they would not succumb to sexual temptation” (biale, 1997:p49-50)[95]

(g.u.s.: a world reference atlas, http://www2.rz.huberlin.de/sexology/gesund/archiv/gus/middleeastold.htm)

so jewish law allows men to marry twelve year olds, whom today would be considered “child brides”. but the plot thickens! even the age limit of twelve is not absolute.

rather, twelve years old is merely the age at which a girl can herself decide to get married. before that, however, her father can have her married off, without her permission.

we read from the website of the special rapporteur to the united nations:

according to jewish religious law (halacha), which in israel confers validity on the marriage of jews conducted within its borders, it is possible to marry a young girl of any age, but the girl herself may decide to marry only when she has reached the age of 12 and a half.

(u.n. representative, http://www.right-to-education.org/content/age/israel.html)

the authoritative jewish website, askmoses.com, says:

what is the minimum age of marriage according to jewish law?

by rabbi naftali silberberg

…in ancient (and not so ancient) times however, marriage was often-times celebrated at a rather young age. although we do not follow this dictum, technically speaking, a girl may be betrothed the moment she is born, and married at the age of three. [shulchan aruch, even haezer 37:1.] a boy may betroth and marry at the age of thirteen. [shulchan aruch, even haezer 43:1]

(askmoses.com, http://www.askmoses.com/article.html?h=573&o=2488)

the talmud recommends that a daughter be given in marriage at around the age of twelve (i.e. the commencement of puberty), but jewish fathers were historically allowed to marry their daughters off even before that age. surprisingly, the wife could be as young as three years old. according to jewish law, such marriages were officially sealed by the man having sex with the baby. we read:

in the ancient world, jewish law seemed to require an act of intercourse for a betrothal to be recognised. the mishnah said: "a girl three years old and one day may be betrothed by intercourse […]" (mishnah, nid. v. 4). maimonides (a. d. 1180) states: "if she is three years and one day old she may be betrothed by an act of intercourse, with the consent of her father. if she is less than that, and her father has her betrothed by an act of intercourse, she is not betrothed"([1972:p18][78]). edwardes (1967a:p168)[79]: "the early-marriage tradition of israel found acceptance in christendom, whose precocious children bedded and wedded at or even before puberty...at the time of st. paul, girls were married at puberty or a little before.

(g.u.s.: a world reference atlas, http://www2.rz.huberlin.de/sexology/gesund/archiv/gus/middleeastold.htm)

although twelve was set as the recommended age, jewish fathers were marrying their daughters off well before that. we read:

although the talmud recommended that a daughter be given in marriage when na'rah, between the ages of twelve and twelve and a half, a father could marry her off well before that time…16th century jewish history reveals a prevalence of girl "child" marriage, many of whom were between 12 and 14 years of age (lamdan, 1996)[86]

the early marriage age may be attributed to several factors: an attempt to prevent the temptation of sexual relations before marriage; the effort to arrange the best possible match both socially and economically; the insecurity of diaspora jews during the age of expulsions from spain and ottoman expansion, moving them to establish ties that would assure the children's financial future; and the desire to raise a new generation of jews as quickly as possible to assure the continuity of their people.

(g.u.s.: a world reference atlas, http://www2.rz.huberlin.de/sexology/gesund/archiv/gus/middleeastold.htm)

according to many jewish scholars, a girl should be married off as soon as she hits puberty and no later. the jewish encyclopedia says:

age for marriage

the first positive commandment of the bible, according to rabbinic interpretation (maimonides, "minyan ha-miẓwot," 212), is that concerning the propagation of the human species (gen. i. 28). it is thus considered the duty of every israelite to marry as early in life as possible…some urge that children should marry as soon as they reach the age of puberty.

(jewish encyclopedia, http://www.jewishencyclopedia.com/view.jsp?letter=m&artid=216)

in the journal entitled women in judaism, we find that jews were still marrying at the age of puberty up until world war i:

a daughter’s coming of age

in earlier days, girls got married at the age of nine…[following the] custom of marrying daughters at age eight to ten…if the maiden does not get married until the age of fifteen she has no hope of marriage, because she would be considered an old maid…at the end of the nineteenth century, despite these regulations, families still married their daughters at the age of twelve and thirteen…on the eve of world war i, the situation changed somewhat for the better when the legal age for marriage was raised to fifteen.

(women in judaism: a multidisciplinary journal,

http://www.utoronto.ca/wjudaism/journal/vol3n2/sehayek.html)

jewish girls “got married at the age of nine”, a practice which continued up until “the eve of world war i”. why then are the jews criticizing prophet muhammad (peace e upon him) for marrying aisha (peace be upon her) at the age of nine? is this not hypocrisy? is this not a case of living in a glass house and throwing stones? why is it that christian adversaries condemn muslims but say nothing at all to their jewish counterparts?

to conclude, we close with the words of mark e. pietrzyk:

according to the talmud, the recommended age for marriage is sometime after twelve for females, and thirteen for males. marriage below these ages was generally frowned upon. however, a father was allowed to betroth his daughter to another man at an earlier age, and sexual intercourse was regarded as a valid means of sealing a betrothal. the age limit for betrothal through sexual intercourse was shockingly low. according to the talmud, “a girl of the age of three years and one day may be betrothed by intercourse.”

(mark e. pietrzyk, http://www.internationalorder.org/scandal_response.html)