The road followed by Alboin to reach Italy has been the subject of controversy, as is the length of the trek. According to Neil Christie the Lombards divided themselves into migrational groups, with a vanguard scouting the road, probably following the Poetovio - Celeia - Emona - Forum Iulii route, while the wagons and most of the people proceeded slowly behind because of the goods and chattels they brought with them, and possibly also because they were waiting for the Saxons to join them on the road. By September raiding parties were looting Venetia, but it was probably only in 569 that the Julian Alps were crossed at the Vipava Valley; the eyewitness Secundus of Non gives the date as May 20 or 21. The 569 date for the entry into Italy is not void of difficulties however, and Jörg Jarnut believes the conquest of most of Venetia had already been completed in 568. According to Carlo Guido Mor, a major difficulty remains in explaining how Alboin could have reached Milan on September 3 assuming he had passed the border only in the May of the same year.