It's not strictly necessary, but it's probably preferable if you do. If you have a bachelor's/master's in a closely-related subject (e.g. political science, area studies, or another social science), and you can demonstrate that you have the requisite research/writing/language skills to carry out historical research, then you can probably get by with that; it just depends on the program, so make sure you look at the specific requirements before you invest the time and money to apply. I can't speak to this from experience since I did a history undergrad before starting my Ph.D. program, and I've certainly never sat on an admissions committee, but anecdotally I do know people who went from other social sciences to doctoral programs in history and did fine.

I'm not entirely sure what you mean by "how was it"; can you elaborate more on that, maybe give some specific questions that you'd like to know the answer to? I think most of us will say positive things about our Ph.D. programs in general, but might be able to offer more specific critiques/advice if we know what kind of information you want.

Also, I want to attach my obligatory advice for these types of questions: do not get a Ph.D. in history because there are not enough jobs and it's a poor career decision. I'd be happy to answer any questions you have, but the number one thing you should take away is that getting a Ph.D. in history is just not a good idea in 2021.

I'm currently in my programme and did my undergraduate degree in Sociology. A history undergrad is not necessary but most programmes will require a certain number of credit hours to be history courses. Additionally you can expect more scrutiny from the admissions committee. Your writing sample should be reflective of the skills required for good history writing or ideally be a good piece of history writing.

It's worth noting this is a US perspective and my sociological research background was historical sociology.

Best of luck!

As an alternative, you could take some courses at a community college and then try to break into a PhD (or more realistically a masters program.)

But as someone who also considered this, practically everyone I talked to advised against it so unless you can not imagine doing anything else but history in your life and you're also ready for the prospect that most history PhDs don't end up staying in academia (or getting into academia more accurately Ig lol), don't go for it.

No, at least in the United States, it is possible to be a strong applicant without a history major in your bachelor's degree or a master's degree in history. The volume of applicants is not so large that such applications are simply screened out without any review.

A strong application from a non-history major would show at least some history coursework and a reasonable connection between the applicant's prior studies and goals in a graduate program in history. For example, you are interested in 20th-century Middle Eastern economic history, you double-majored in Middle Eastern studies (which included three history courses in which you did well) and economics, are fluent in Arabic and working on your Turkish, wrote a thesis on a historical topic like early 20th century economic development in Syria, and have a letter of recommendation from a history professor--thus you should be fine. (I myself majored in religion and medieval studies and got into a history M.A./Ph.D. program to study medieval European religious history.)

As others will say, think very hard before going to grad school in history. Career prospects are extremely poor. Only consider the absolute top programs and potential advisors. You should not even think of attending unless you receive a "full ride" of tuition remission, scholarships, grants, etc. to cover living expenses and research.