Dogs migrated alongside humans but the movement of the two did not always align, indicating that in some cases humans migrated without dogs or that dogs moved between human groups, possibly as a cultural or trade item. Dogs appear to have been dispersed across Eurasia and into the Americas without any major human population movement being involved, which remains a mystery. Past studies have suggested the dog's place of origin but these studies were based upon today's patterns of genomic diversity or possible links to modern wolf populations. The dog's history was obscured to these studies because of recent gene flow and population dynamics – the geographical origin of the dog remains unknown.