Black wins

Black is under the threat of mate in 1, but it's black's turn...
Black to play and win.

Bonus questions:
Can you guess how long ago was this problem composed?
The author of this problem composed many other problems, but most of them are rarely reproduced today (they are not lost, and they are sound). Explain why.

Originally posted by David113
[fen]1r1r4/8/1n6/2p5/2P5/1NK5/R3R3/1k6[/fen]

Black is under the threat of mate in 1, but it's black's turn...
Black to play and win.

Bonus questions:
Can you guess how long ago was this problem composed?
The author of this problem composed many other problems, but most of them are rarely reproduced today (they are not lost, and they are sound). Explain why.

1. ..... Na4+
2. Rxa4 Rxb3+
3. Kxb3 Rd3#

Looks fine to me (but I've been wrong before). There are only a limited number of initial moves as whites' threats mean that only a key move with a check will suffice.

As to the age, I have little idea, but the most likely thing I can think of is that it dates from a time when the rules differed slightly. So although sound under the composers rules, they fail under those used today.

It isn't one of Samuel Lloyds problems, is it?

Originally posted by David113
[fen]1r1r4/8/1n6/2p5/2P5/1NK5/R3R3/1k6 b - - 0 1[/fen]

Black is under the threat of mate in 1, but it's black's turn...
Black to play and win.

Bonus questions:
Can you guess how long ago was this problem composed?
The author of this problem composed many other problems, but most of them are rarely reproduced today (they are not lost, and they are sound). Explain why.

1...Na4+ 2.Rxa4 Rxb3+ 3.Kxb3 Rd3#

Bonus:
1) About 700 years ago.
2) Back then, 'chess' was 'shatranj' - different rules, especially the movements of pawns, Bishops and Queens.