Thread: золотою порою

seasons and dayparts (mainly) in Instrumental case mean timing of an event, when the event happened

Лето - летом - in/during summer
Ocень - осенью - in/during autumn
Зима - зимой/ю - in/during winter
Весна - весной/ю - in/during spring
вечер - вечером - in the evening
день - днём - in the day
ночь - ночью - at night
утро - утром - in the morning
пора - порой/ю - at times (inapplicable for this particular fragment)

in the phrase Это было весною it's said that something (это) was or was happening (было), when? in spring/springtime (весною)

had Paul G's translation been accurate, the Russian phrase should have sounded like Это/То была весна, золотая пора (Nominative case)

это было instead of это была (весна) points at an unnamed subject, which is already known to the reader or will be revealed later

judging by the phrase syntax the subject of the poem is not the spring but something that happened during springtime denoted by the word это

Thanks,Yes it happened during springtime,Kazan Kaziev song.