If you are referring to the invasions of the western part of the Roman Empire, the groups were the Vandals Sueves Alans, Burgundians and Alemanni.

In the 3rd century AD the western part of the Roman Empire was raided by the Franks and Alemanni. .The east was attacked by the Heruli and the Goths.

In the 2nd century AD the western part of the Roman Empire was raided by the Franks and Alemanni . The eastern part was attacked by Marcomanni, Quadi, Iazyges, Naristi, Chatti, Chauci, Langobardi, Hermunduri, Suebi, Buri, Cotini, Vandals, Roxolani, Bastarnae, and Costoboci.

You should tell what the groups listed in the question are. In the first century it was attacked by the Persians. In the second century the Roman Empire was attacked by the Persians, Marcomanni, Quadi,Iazyges, Naristi, Chatti, Chauci,Langobardi, Hermunduri,Suebi, Buri, Cotini,Vandals, Roxolani,Bastarnae, Costoboci. In the third century it was attacked by the Franks, Alemanni, Heruli and Goths. In the fourth century it was attacked by the Persians, Franks and Alemanni. In the fifth century it attacked by the Huns and invaded invaded by the Vandals, Sueves, Alans, Burgundians and Alemanni. The Angles, Saxons, Jutes and Frisians migrated to England in waves.

Many external gropus were a threat to Roman security at one point or another: the Persians, Marcomanni, Quadi, Iazyges, Naristi, Chatti, Chauci, Langobardi, Hermunduri, Sueves, Buri, Cotini, Vandals, Roxolani, Bastarnae, Costoboci, Goths, Heruli, Alemanni, Franks, Hunns Alans, and Burgundians.

In the end the Vandals, Alans, Sueves, Burgundians and Alemanni invaded the western part of the Roman Empire. The Angles, Saxons, Jutes and Frisians migrated to Britain in waves and took it over.

Most of these peoples were of Germanic or Iranian stock.

The Romans had a great many enemies over the 1,200 years of history.

They were: other Latin cities, Etruscan cities, the Sabines, the Volsci, the Aequi, the Samnites, the Umbrians, king Pyrrhus of Epirus, The Carthaginians the Illyrians, the Gauls of northern Italy, The Macedonians, the Aetolian League, the Seleucid Empire, the Achaean league, king Mithridates Vi of Pontus and king Tigranes II of Armenia, King Jugurtha of Numidia, the Cimbri, the Teutones, the Lusitans, the Celtiberians, the Cantabrians, the the seves, the Harudi, the Belgae, the Gauls of France, the Persian Empire, , the Cherusci, the Bructeri, the Chatti, the Jews, the Dacians, The Marcomanni, the Quadi, the Iazyges, the Cauchi, the Hermunduri, the Lombards, the Costoboci, the Buri, the Naristi, the Cotini, the Roxolani, the Bastarnae, the Garamantes, The Alemanni, the Sarmatians, the Carpi, the Goths, the Heruli, the Scythians, the Juthungi, the Vandals, the Franks, the Blemmyes, Radagaisus, an (Ostrogoth king) the Alans, and the Burgundians.

This list does not even attempt to be exhaustive. With so many enemies, the reason for having enemies varies from circumstance to circumstance.