Ruled to II 3434 The earliest recorded King of Lórien was Amdír, otherwise known as Malgalad2. It's not clear whether there were any earlier Kings than this, but what is known is that this King ruled during the Second Age, and met his end fighting with the Last Alliance in the Battle of Dagorlad
How the first King of Lórien emerged is something of a mystery, but there is a clue in the fact that Amroth is described as being of Sindarin descent. We know that many Sindar set out from Lindon after the end of the First Age, and that at least some of them established realms of their own. While Lórien is not explicitly named as one of these, Amroth'sSindarin origins point strongly in this direction. If this is correct, it implies that Amroth's father Amdír (or Malgalad) was the first King, and established his realm fairly early in the Second Age.
2
The names Amdír and Malgalad occur in different versions of the history of Lórien, and they presumably refer to different individuals. However, given that all these histories end with Amdír/Malgalad suffering the same fate at the Battle of Dagorlad, it's conceivable that they were different names for the same person, in the same way that Ereinion was also known as Gil-galad.