According to Jesus, Galilean street children would play flutes and expect other children to dance (Mt.11:17, Lk.7:32). Matthew (14:6) uses this same word (orcheomai) when Salome dances for her stepfather, as does Mark (6:22). In its only four NT appearances, the same word refers to a dance kids can do in the street, and to whatever Salome did. We can only imagine the details.
Shamefully, however, many commentators have assumed Salome's dancing was lascivious, and Herod's "pleasure" was improper. Of course, it wasn't so long ago in the Puritan USA that any dancing was considered lewd, except perhaps childhood jigs. To be fair, though, Matthew's account does seem to set both the dance and its offered rewards in a private one-on-one setting. Or, does it? We don't know what Matthew's audience would assume about a "birthday" celebration - but it's possibly NOT the same thing modern hedonists might be thinking today.
Fortunately, Mark's account implies something much more specific, which also happens to seem much more innocent. Mark puts both dance and promise in the middle of a party, says plainly that Salome's dancing pleased both "Herod and his dinner guests", and cites the oath as a phrase from the Esther story.
Furthermore: Since this "birthday" feast likely fell soon after Purim, and if Herod's remark came down accurately, it seems the dinner host was cleverly referencing that prior feast night, where a professional orator would have given the traditional Purim tale. All that may seem by the by, but if valid it helps complete the picture of what may have been going on.
Put together, all of this clearly suggests that a harmless, plafull interaction is what probably happened here. Salome's dance need have been nothing more than a preteen or young girl performing her tricks for the family's guests. That is all. Neither Matthew nor Mark suggests that Herodias had anything to do with promoting the dance. Neither Gospel paints this as a plot from the beginning. In both Matthew and Mark, the mother's scheme begins only after the girl doesn't know what to ask for. That itself might possibly speak to her age... but we have better recourse than that.
In considering Salome's historical age on that night, we actually do have some slight clues. First, since the girl was still strongly influenced by her mother, she must not have been married, and thus cannot have been very old. But since her future husband, her uncle Philip, dies in AD 33/34, we must also presume Salome was at least 13 by that year. Thus, if John is beheaded in AD 31 (or AD 29, or AD 32(*)), the dancing girl may have been as young as 11 (or 9, or 12, respectively(*)). At least, those are the early limits.
Interestingly, these competing chronologies (*below) all agree in making Philip's marriage fairly brief - only about 2 years (or 4, or 1(*)). What we don't know is how old Salome was when she married him. But just for example, let's suppose she was married by seventeen, at the latest. If so, and if she married Philip as late as possible, in 33, then Salome's infamous dance would have occurred at age 15 (or 13, or 16(*)). But supposing she married at seventeen, and married just after dancing, then she would have been 17 when she danced.
This all seems simple enough. If Salome married young, then she danced even younger. Still, the early part of our range here seems surprising. Could the dancing girl really have been so young as 11 (*or 9, or 12)? It's an age worth considering, at least as likely as the older end of our range, and it could help some to imagine a more innocent context for Antipas' appreciation of her performance, which - whatever Salome's age - is probably more fitting to what the Gospel accounts offer, anyway. On the odds alone, Salome was probably midway between 11 and 17 when she danced. (And 11 to 15 on my own preferred chronology.) But anywhere in this range, we should not assume Herod was pleased because of improper thoughts.
There are dancers who dance for lascivious men, and there are dancers who dance for the sake of the dance, but a class above all these are rich daughters who get called upon to entertain family guests at a party. If this particular girl's most showcase-able talent was dancing, then we ought to be confident she took some care for performing it well, and that to some degree she probably regarded it as her art.** In other words, some of us need to exorcise what those old dance-o-phobes passed down about this passage, for as much as it's still in our memories.
Historically, I'd guess Salome was 13 when she danced, simply because I don't think Uncle Antipas would have waited much longer than that to "sell" her to his brother Philip. But even at 15 or 17, I suggest all evidence leads us to conclude that the evening's entertainment was in some style of dancing that would have been considered completely appropriate for a large gathering, in those days. Herod's showy largess could have been customary or spontaneous, but Herodias couldn't have known he would offer her "anything".
Mommy just took advantage of a nice little surprise. The dance wasn't calculated to exact a beheading.
*On the competing chronologies, referenced above: The first numbers listed, before each parentheses, correspond to my own timeline. After that, the asterisked, parenthetical numbers correspond to Meier's [the standard two-year] & Hoehner's Chronologies, respectively.
**Full disclosure: my own daughter, age 9, is a budding dance artist, and has loved taking dance for six years. In my early life, the only dancing I saw was on MTV and during halftime shows. Ballet was a snoozer back then, but it's not any more. It's like any other art, or sport. Once my dad taught me golf, I found an appreciation for watching (!) golf. So, back to my dancing daughter - as grateful as I am for this wonderful girl, I must confess that her influence did not occur to me until after the first draft or two of this post. At least, not consciously. But she has taught me a lot about dance. PTL.