There is currently an attempt to close this question on the grounds that it belongs on history.se. We have had questions about the state of law in past times, such as a question about divorce law in 1940 Ireland. Are such questions on-topic here?
The relevant page on the help center includes "Historical legal applications" as one of the specifically on-topic categories. That a question might be on topic in more than one SE site is not a reason to move it or close it.
Yes, this is quite obviously on topic. The development and history of the law is perfectly on topic here, even if it is also on topic elsewhere.
Similarly a question on topic at Stack Overflow might simultaneously be appropriate for Android.SE and or CodeReview.SE, but that doesn't mean the question needs to be kicked to the the group with the narrowest niche, which seems to be what the close-voters are trying to do here.
It seems quite obvious that the vast majority of questions on social science are going to be at least somewhat interdisciplinary, so it's a rare question that would only be on topic at Law.SE. I could just as easily say, for instance, that we should bounce all our Covid questions to MedicalSciences.SE, or that all our employment-discrimination questions should be bounced to Workplace.SE, or that all our copyright questions should be bounced to Writing.SE or Photography.SE or Video.SE.
The users of those pages would undoubtedly have their own ideas and perspectives that they could bring to bear on questions, but maybe it makes more sense to defer to the OP as to which community and perspective he's looking for, rather than booting them just because it's possible to boot them. If someone wants a historian's perspective, let them go to History.SE. If they want a legal perspective, let them come here.
Are questions about the law in past times on topic here?
IMO yes, and I concur with the answers given by David Siegel and bdb484.
I'm relatively new here and still finding my feet, but I see one role of LawSE to be a repository for reputable and verifiable sources for all (most) aspects of the law in order to, for example, aid and inspire academic study or just for general interest. Notwithstanding the cited cross-overs with other SE sites, this would undoubtedly include its evolution and development over time in reaction to changing socio-political attitudes etc.
Also, having a wide and varied content of on-topic posts may help to promote the site up the list of internet search returns, thus attracting new users and contributors.