That the ceremonial garments, carefully embroidered by hand, referred to Allah instead of God , Jesus or Pagan gods has people speculating.
Viking graves and other Viking artifacts include items from other cultures. Many are presumed to have the spoils of plundering. The silk burial fabric, however, appears to have been made by Viking people themselves.
Use of silk fabric is mentioned in Islamic literature as a way to insure passage to the promised land. That further interests those studying Viking culture and the burial costumes.
There is evidence Vikings visited Islamic countries in a earlier time. It is not, of course, certain those buried in costumes which bare tribute to Allah were Muslims. Certainly, it becomes something to consider.
These fabrics were discovered long ago but no one studied the inscriptions until recently. It has started renewed interest in the burial dress. Both males and females wore the silk fabric.
While the Vikings are generally thought to have been warriors and plunderers, there is now some consensus they were, instead, interested in commerce and assimilation. They adopted the religions and cultures of places they conquered. If this pattern held true they may have picked up some affection for Islam and later dropped it for something else.
The Viking period of conquest was about 1,000 years ago. After a few centuries the conquests stopped with Vikings settled in several places in the world.
It is a little hard for a person like me of Christian Scandinavian heritage to grasp the religious/cultural diversity of these people.