Viking Treasure in 3000 Year Old Grave

During excavation for a new railroad in Uppland county, Sweden a 3000-year-old grave was found with 163 silver pieces found from the Viking age. The silver coins found had Arabic inscriptions on them. This finding is the largest find of a Viking treasure ever found in Uppland county.
Many Vikings hid treasure during wars to come back and retrieve later, however at the time that this treasure was buried in the then already existing grave there was no war going on. So this brings a question to my mind. Why bury treasure in a grave that at that time was 2000 years old. Many Vikings would bury things to have with them in the afterlife, but how come an already existing grave.
The coins that were recovered were from Samarkand, Volga, and modern Russia and are imitations of the Arabic coins. The youngest coin was produced in 935 A.D. or 936 A.D. and was hidden about 20 years later. This is not the first connection between the Viking Age Scandinavians and the Islamic world.
Could this have been an action to assist a long-dead ancestor or noble in the afterlife? Please give your own opinions and questions.
[DISPLAY_ULTIMATE_SOCIAL_ICONS]