Mallor's reign saw events that would have a huge impact on Middle-earth's history, but whose importance wasn't fully recognized at the time. The first of these was the arrival across the Misty Mountains of a strange race of beings, similar to Men, but far shorter and with hairy, bootless feet. The Dúnedain called them periannath, 'halflings', and they were the first Hobbits to enter the western lands.
The second historic event was the descent of a strange shadow on Greenwood the Great. This was wholly mysterious at first, but before the end of Mallor's reign, the Wise had discovered that its source was at Dol Guldur in the southern part of the Forest. It was not discovered until long after Mallor's time that his reign had seen the return of Sauron himself, the first move in a game that would end in the War of the Ring nearly two thousand years in the future. It was soon after the appearance of this shadow, that the Istari - the Wizards - arrived in the north of Middle-earth.
The date of Mallor's birth appears only in The History of Middle-earth volume 12, The Peoples of Middle-earth. It cannot therefore be considered completely reliable.
The meaning of Mallor's name is not explained, but it appears to include an Elvish word meaning 'gold' (and this is supported by the fact that the three Kings who followed him - Celepharn, Celebrindor and Malvegil - all seem to reference silver or gold in their names). The -lor ending may also be interpreted 'gold' (hence Mallor would be doubled 'gold'), or may be an agental ending (suggesting that Mallor was famous for collecting or providing gold).