encroachment

my parents bought an 8 acre tract of land about 3 years ago in arkansas. at the time they bought it a neighbor was driving across it to get to their property. they knew this when they bought it. the neighbors have another way (county road)in to their property, however it is a much longer drive on a gravel road. do my parents have a legal right to fence their property and keep the neighbors from crossing it even if the neighbors assumed they had a legal right to cross there when they bought their land? also can the neighbors assume right to the road they are using on my parents property after a period of time of using it with my parents knowledge?

[HomeGuru]

Yes, their land can be fenced in.
Yes, the neighbors can claim an easement by prescription.