Probably so. There are a bunch of facts which would need to be discussed before a definite answer could be given. For instance, how long have they been living there, did they have a lease with the people from whom you inherited the land, was that lease recorded, and others. I suggest you discuss this with a lawyer to see what can be done.
My comments are based only on the information presented in your question. I have not been retained as your lawyer, and do not possess enough information to give you a legal opinion on the outcome of your dispute. I recommend that you retain a lawyer to advise you before making any decisions relating to the issues raised in your online inquiry. I recommend that you retain a lawyer quickly, because there may be time limits which impact your legal situation. I HAVE NOT PROVIDED ANY LEGAL ADVISE TO YOU AND URGE YOU TO GET A LAYWER.
If they have a lease of some sort, it may still be in effect even though you bought the land. If they are trespassers or their agreement was only with the original owner, you will probably have to start an eviction proceeding. But without knowing more, it is impossible to say. They may even have a life estate or some other arrangement allowing them to be there, but all this should have been disclosed to you when you bought the property. If not you may well have a cause of action against the seller, the broker and realtor. It all depends on the facts. If these people were in plain site for you to see, you may be presumed to have knowledge of them without anyone telling you.
What do the people there say? Ask first, then if need be, see a good lawyer to advise you.
This response is not to be construed as establishing an attorney-client relationship, and provides general information on the subject at hand only.
I agree with the answer that you need to talk to an attorney. To make the best use of that time, gather all the documents that you can about the property. Get the deed from the estate, or if there is some other paperwork, have whatever probate or other documents demonstrate that you now own the land. If you have any information about the mobile home and its owner, when it was put on the land, etc., get all of that together too. Does it have electricity? Whose name is on that bill? Same for water or sewer, if the land has those.