For Darans (citizens of the empire as well as Daran descended populations in the Darian states and elsewhere) it is considered bad luck for anyone to know where a loved one is buried, though the body must actually be buried. Cremation is acceptable but the ashes must be buried as the body was - it's more of an intermediate step that removes the need for preservation if burial must be put off. It is also unlucky to admit to outsiders that a person is dead for seven days after the actual event - even family members who are not nearby will not be informed until after this time.
The people who bury bodies, called "Keepers", are highly respected in society, but aren't actually part of the social realm - it's considered unlucky to talk to them, though they are very well compensated and respected. In modern times bodies are buried in burial grounds so that the general area is known rather than taken into the wilderness, but no markers are left.
The origins of this custom are lost in time, but definitely go back to pre-imperial days.