Though there had been some immigration from Scotland to Europe in previous times it was from the later sixteenth century onwards that the phenomenon of the movement of people out of Scotland really got going in contrast to the previous millennia of inward migration. This meant that as well new ideas and technologies coming in to Scotland there were now also learned directly in other countries where more advanced techniques had been developed. The population of Scotland is thought to have doubled in the century after 1550 which together with the growth of the economy in the long reign of James VI prompted these massive population movements. This movement of population to countries such as Poland, Sweden and the Baltic region as a whole was also matched by a hugh growth of trade from Scotland to these countries. A darker side to this migration is illustrated above with large numbers of mercenary soldiers taking part in the conflicts of the period particularly in the appalling Thirty Years War which destroyed much of central Europe. Though the bulk of this immigration was before 1650 some continued well in to the eighteenth century in to Prussia and Russia; thereafter it becoming increasingly concerned with trade.