The name Stockholm first appears in historical records in letters written by Birger Jarl and King Valdemar dated 1252. However, the two letters give no information about the appearance of the city and events during the following decades remain diffuse. While the absence of a perpendicular city plan in medieval Stockholm seems to indicate a spontaneous growth, it is known German merchants invited by Birger jarl played an important role in the foundation of the city. Under any circumstance, during the end of the 13th century, Stockholm quickly grew to become not only the largest city in Sweden, but also the "de facto" Swedish political centre and royal residence. Thus, from its foundation, Stockholm has been the largest and most important Swedish city, inseparable from and dependent on the Swedish government. However, as late as the 16th century, reigns of Kings Eric XIV and John III, whose Swedish government often travelled with them elsewhere (see below), the city was still not what could be called a national capital in modern terms.