This letter was sent after Melania the Elder visited Nola and before Sulpicius' basilica was dedicated, hence in 402 or 403.
Melania the Elder visited Nola after she came back from Jerusalem (where she lived for twenty-seven years) in the very end of the 4th century.
Primuliacum was one of Sulpicius' estates that he did not sell when he was rejecting his wealth [2095]. Its exact location was lost. Recently, Frank Riess (Riess 2013: 66-69) has, once again, proposed the identification of Primuliacum with Elusio, present-day Monferrand, which Paulinus mentions in his first letter to Sulpicius ([2055]). The hypothesis that it also served as the later site of Sulpicius’ monastery is strengthened by the recent excavations of two 4th- or 5th-century basilicas, positioned side by side, just as in Primuliacum (see the beginning of letter 32 [2108]).
Bassula was Sulpicius' mother-in-law, see letter 3 of Sulpicius which is addressed to her, [980].