Some archaeological evidence of so called Slavic 6.AD Worldwide migration

 Some archaeological evidence of so called Slavic 6.AD Worldwide migration 

1. First evidence is existing of limited physical evidence that Slavic migration happened.

2. Second and last one evidence are written sources.

Although it is still widely accepted to have existed ,these physical evidences i.e. Academic facts are based at 6 cen A.D. written sources only.

"From an archaeological point of view, these migrations are manifested in the spread of Slavic cultural traits (related to handcrafted ceramics, types of buildings, cremation tombs, and female costume), and, for the southern part of the area, they are confirmed by the testimony of written sources.." 1

And ...

Because there's nothing of remaining archaeology the Archaeologists themselves are with :

  "Currently, there are three main hypotheses for the spread of Slavic between about 400 and 850 CE, e.g., [6, 7]. The first hypothesis assumes that speakers moved in all directions from their small original habitat, the so-called Urheimat, e.g., [8–10]. The second hypothesis assumes the diffusion of the Slavic cultural model among non-Slavic populations or, in its extreme form, the diffusion of language alone, e.g., [7, 11–14]. Many archaeologists adhere to the third, hybrid hypothesis. The hybrid hypothesis states that movement, cultural diffusion, and language diffusion occurred simultaneously [15–18]. This is supported by recent research in population genetics and linguistics.."2

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Ref : 

1. Michael Kazansky ," Archaeology of the Slavic Migration", Encyclopaedia of Slavic Language an Linguistic ,Praga

2. Source 

"15. Kazanski M. Archaeology of the Slavic Migrations. In: Greenberg ML, Grenoble LA, editors. Encyclopedia of Slavic Languages and Linguistics. London, New York: Brill; 2020. doi: 10.1163/2589-6229_ESLO_COM_035967 [CrossRef] [Google Scholar]

16. Pleterski A. Etnogeneza slavena—metode i proces. Starohrvatska prosvjeta. 2013;40: 8–32. [Google Scholar]

17. Pohl W. The Avars: a Steppe Empire in Europe, 567–822. Ithaca, NY: Cornell University Press; 2018. doi: 10.7591/9781501729409 [CrossRef] [Google Scholar]

18. Heather P. Empires and barbarians: The fall of Rome and the birth of Europe. Oxford: Oxford University Press; 2010. [Google Scholar] " 

Link 

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9484688/