BC dates have wrong datatype, are missing the negative sign, or are missing

I have an old partial DBpedia persons dump including negative (BC) birth and death dates such as this:

Brutus_of_Troy deathDate "-1125-1-1"^^xsd:date .

However when checking those persons on current DBpedia, I got different results when checking some of them:

  • dbpedia:Brutus_of_Troy does not have a death date anymore (“-1125-1-1”^^xsd:date before)
  • dbpedia:Bryson_of_Heraclea used to have a death date of -400-1-1"^^xsd:date ., also does not have one anymore
  • dbpedia:Empress_Dowager_Bo used to have death date “-155-1-1”^^xsd:date, now it’s “155”^^xsd:integer
  • Yāska had dbo:birthDate -500-1-1"^^xsd:date, on current DBpedia the value is is 7 (xsd:integer) (wrong datatype, missing sign, wrong magnitude as she is estimated to have been living somewhere between 500 and 700 BC)

P.S.: Error while posting, had to remove the links because only 2 links are allowed.
P.P.S.: According to ISO 8601 - Wikipedia, years before 1583 are a nonstandard expansion, however they should be valid xsd:date values.