Parts of Moone, Kilkea and Dunlost, five miles south-east of Athy, came to the Eustaces in 1447 as part of the Wogan inheritance and by 1485 Edward Eustace of Clongowes Wood had acquired Mullaghcash, four miles south of Naas, and probably the adjoining estate of Mylerstown. During the next century we constantly meet Eustaces of Kilkea, Moone, Timolinbeg (just north of it), Mullaghcash and Mylerstown. From these came Roland Eustace of Mullaghcash who died in 1569 and was succeeded by his eldest son Thomas Eustace. He married first Cicely, daughter of William Gaydon of lrishtown and secondly a Catherine Eustace. He died in 1594 leaving, with five other Sons: OLIVER his heir; Elizabeth who married Walter Archbold of Timolin (who died in 1629 and their tomb is in Moone Abbey); and Joan who married Oliver Eustace of Blackhall (q.v.). By 1584 he had regained his lands forfeited after the Baltinglass rebellion. At this time the Moone estate also included the nearby townlands Symonstown, Commonstown and Kilbeaghan.

Oliver Eustace, of Moon and Mullaghcash, an important man in the county, was born in 1566 and married Mary, daughter of Maurice Fitzgerald of Glassealy and his wife Honora O’Toole. Honora outlived her husband and in 1615 bequeathed half her estate to Mary. Oliver had a son William Eustace a juror in 1608, and grandsons Thomas, Oliver and Roland, who lost their lands in 1641. Moon was bought by William Ashe, a rich Dublin Alderman, while the lands south of Naas came to the Lord Chancellor by grant or purchase. The estate of Mullaghcash (which included Mullaghcash, North, Middle and South Flemings town, and Tonaphuca (Flemings town South) descended to Penelope Echlin, nèe Eustace, but was sold by the 3rd Baronet in about 1750 and soon afterwards was bought by Mr. La Touche. Mylerstown was sold in 1721 for about £8,000 to meet claims against the estate of Sir Maurice Eustace of Harristown. (The estate of Maurice Eustace included Mylerstown, (except a small plot held by the Earl of Kildare), Oldtown, Stephenstown, North and South, and the unidentified Ballynure, Colelane and Coleneboenly, said to be 24 miles from Dublin.)

The ruins of Mullaghcash and Killashee Castles remain, but no stonework is left on the sites of Mylerstown Castle and the castles (also shown on a seventeenth century map) at Oldtown Villa and on the small rise half-a-mile east of Mullaghcash. One document shows that the Lord Chancellor Maurice Eustace received Killashee just north of Mullaghcash on forfeiture by Richard Bealing but we hear no more of it.

These castles no doubt defended the Pale when it ran straight from Castlemartin to Clongoweswood.