Maps showing distribution of Franks name by century

It can be seen from the maps that although the name Franks is widely distributed it is concentrated in the central and eastern counties of England. Could the meaning of the name in some way be tied to this dependent on profession? Or do the maps just show migration due to socio-economic changes?

  • Upto 1600

    map upto 1600
  • 1601 - 1700

    1601 - 1700
  • 1701 - 1800

    1701 - 1800
  • 1801 - 1900

    1801 - 1900