I inherited my acreage from family in 1997, therefore never had survey done. My new neighbor that purchased land that borders 2 sides of my land, states that his survery shows my fence is over on his side by 30 ft on one side and 40 ft on the other side. He broke the lock on my gate and entered my pasture with equipment and started digging holes and placing posts in the ground to put new fence and I had to call the sherriff and they have told him to stay away until it's determined if he has right to property. Do I have to move my fence, since it has been in place since my family bought it in 1971?

First you need to get your own survey done to see if this is true.

Were there markings visible where his survey team marked.

After you have your survey, if it proves that they are on his property, then you will have to file in court to take ownership of his land because of the factor you have had it and used it and it was fensed for that number of years.

The laws on this vary greatly by state.