Here, from 428 BC, is a rather complicated real estate lease with a 60-year(!) term. 20 talents of dates per year, plus a number of other clauses and considerations.
Baga'miri, son of Mitradatu, spoke of his own free-will to Belshum-iddin, son of Murashu, saying: "I will lease my cultivated field and uncultivated land, and the cultivated field and uncultivated land of Rushundati, my father's deceased brother, which is situated on the bank of the canal of Sin, and the bank of the canal Shilikhti, and the dwelling houses in the town of Galiya, on the north, adjoining the field of Nabu-akhi-iddin, son of Ninib-iddin, and adjoining the field of Banani-erish, a citizen of Nippur; on the south, adjoining the field of Minu-Bel-dana, son of Balatu; on the east, the bank of the canal of Sin; on the west, the bank of the canal of Shilikhti, and adjoining the field of Rushundati, the overseer (?) of Artaremu---all to use and to plant for sixty years. The rent of the cultivated field will be twenty talents of dates; and the uncultivated field (I will lease) for planting." Afterward Bel-shum-iddin, son of Murashu, accepted his offer with reference to the cultivated field and the uncultivated field, his part and the part of Rushundati, his uncle, deceased; he shall hold for sixty years the cultivated portion of it for a rental of twenty talents of dates per year, and the uncultivated portion for planting. Each year in the month Tishri, Bel-shum-iddin unto Baga'miri will give twenty talents of dates for the use of that field. The whole rent of his field for sixty years Baga'miri, son of Mitradatu, has received from the hands of Bel-shum-iddin, son of Murashu. If, in the future, before sixty years are completed, Baga'miri shall take that field from Bel-shum-iddin, Baga'miri shall pay one talent of silver to Bel-shum-iddin for the work which he shall have done on it and the orchard which he shall have planted. In case any claim should arise against that field, Baga'miri shall settle it and pay instead of Bel-shum-iddin. From the month Nisan, of the thirty-seventh year of Artaxerxes, the king, that field, for use and for planting, shall be in the possession of Bel-shum-iddin, son of Murashu, for sixty years.
A Collection of Contracts from Mesopotamia, c. 2300 - 428 BCE