Trying to take our land

[Lisa DWG]

We live in Ohio and just purchased a house with 3 acres, we have not lived here 2 full years and the neighbors are trying to take almost about 1/4 -1/2 of an acre saying that they have taken care of it for 22 years. I t was up for sale at least 3 times in 22 years, they never tried to purchase it and when we purchased it there were no desputes or leins on property. We asked their lawyer ( yes they did not speak to us about this at all, had a lawyer send us a paper and immediatly brought surveyers out) to tell them to remove thier fence an swing which they have just placed there recently. He seems to think we are in the wrong that since we bought it, Pay the taxes and now care for it and planted plants there that it should still be theirs and is talking about court. Please help, what should we do? Lisa