String jsonText = '{"Data": [{"attributes": {"type": "Contact","url":"/services/data/v35.0/sobjects/Contact/0036100000JUXKkAAP"},"Email":"positi@gmail.com","Description": "","Phone":"9999999","LastName": "sasumi"},{"attributes": {"type": "Contact","url":"/services/data/v35.0/sobjects/Contact/0036100000JUXKkAAP"},"Email":"edge@gmail.com","Description": "","Phone":"88888","LastName": "pavanTL"}]}';

Map<String, Object> deserialized = (Map<String, Object>)JSON.deserializeUntyped(jsonText);
List<Map<String, Object>> data = new List<Map<String, Object>>();
for (Object instance : (List<Object>)deserialized.get('Data')){
    data.add((Map<String, Object>)instance); 
}

String dataSerialize=JSON.serialize(data);
System.debug('dataSerialize...'+dataSerialize);
try
{
   SObject customObject = (SObject)JSON.deserialize(dataSerialize, Sobject.class);
    Database.upsert(customObject);
    System.debug(' customObject...: '+customObject);
}
catch(Exception ex)
{
    System.debug(' @@@@@ Don\'t visible '+ex.getMessage());
}