Nordic people or Caucasian people did not originate light colored eyes.
In fact, it was the other way around. While there is a higher concentration of light colored eyes in Europe, the phenotype (physical attribute) and genotype (genetic attribute) for light colored eyes first made it's appearance in Central Asia.
Genetically, people with light colored eyes can trace their ancestry back to central Asia or the Middle East, very rarely will a person with light eye color in Central Asia trace their genetic history to Europe.
The link to the map shows that the people that went to Northern and Western Europe all originated from central Asia.
Central Asian Genetic marker M45 > North Eastern European Genetic Marker M173 > North West European Genetic Marker M43
Central Asian Genetic Marker M45 > North European Genetic Marker LLY 22
Also note, the Southern European areas show migrations directly from the Middle East, hence the greater number of dark eyed people in Southern Europe as opposed to Northern Europe.
So, genetically, Central Asian people contain the genes for light colored eyes. However, they also contain the gene for dark colored eyes since subsequent migration of people from the Middle East resulted in a higher concentration of dark eyed genes in the gene pool. The people that left central Asia for Europe early had a higher concentration of the light eye color gene in their gene pool and through natural selection, this became even more concentrated especially since there was little to no subsequent migration from the Middle East except for Southern Europe.