Complex sentence: Another MacCulloch family, the MacCullochs of Plaidis, were known to have established themselves in Easter Ross in the Scottish Highlands by the 14th century, where they are first noted as followers of the Earl of Ross and Clan Ross.
Split into simpler sentences: Another MacCulloch family, the MacCullochs of Plaidis, established themselves in Easter Ross in the Scottish Highlands by the 14th century. They were first noted as followers of the Earl of Ross and Clan Ross.