What is comparison of the legal position vs. Islamic jurisprudence on unused land?

For a very long time, there was a barren piece of land. Someone occupied it and began cultivating it. A year after his occupation, we checked the records with the Patwari and the Revenue Department, and it turned out that the land was entirely ours — it had always been registered in our family’s name. The court and the legal authorities have now ruled in our favor. The cultivator has no legal share in the records; there is only a local tradition that our ancestors used to farm this land long ago, but it hasn’t been cultivated by us for the last fifty years. I also heard a narration saying that in Islam, if the owner does not cultivate the land for three years, it can be taken back from him. So from a religious perspective, what is the ruling? According to the law, we have the right to take back the land — but according to Islam, should we give it up?