Greece was the first nation to realize that it had no money to pay the interest as well as the principal and thus would have to default on their payments (Brown, 2012).
For other PIIGS nation, there was huge amount of debt taken by the Italy government. The debt stood at the 125 percent of the whole GDP of Italy. In terms of the amount Italy was not the highest but its debt proportion to GDP was very high and most of the borrowings was in government sector (De Santis, 2012).
Thus all the PIIGS nations were spending uncontrollably and were mounting huge debts without any firm source of revenue for these nations.
Post the existence of Euro, Germany became one of the top exporters across the globe. Germany overtook China and is the largest exporter in the world. As the euro was formed, it helped the Germany to sell the goods to the other European nations. The main advantage for Germany was that there were no currency fluctuations for the nations. Thus the only thing which mattered was the cost at which it produced the goods
Germany was already known for its products and in the European Union it has the best production of goods. The cost efficiency for Germany was huge and it was the best among the European nations. Thus Germany became the exporter and many nations started importing from Germany. As the currency was also same there were fewer hassles plus no currency fluctuations. Just to give an example, Germany was 30% more cost efficient that Greece. Thus Greece imported more than the double goods it exported to other nations.
Another reason for the rising exports of Germany was that the banks provided the loans to the nations at a very lower interest rate. Also since there was a single currency it worked well for the German banks.