Questions about the Persian Empire?

what role does trade and agriculture play in explaining the success of the Persian Empire? why was the Royal Road so important?

Trade and agriculture was all important as it brought the wealth needed to sustain the empire, the royal road being the main highway.
Nobody could travel on this road unless having a pass from the king and even livestock had to be given this pass. The royal road may also have been the first to introduce a pony express system in order to get messages quickly to the king.

US sanctions have hit Persian rugs trade – 16 Nov. 2010

N1979 LIEBIG ADVERT TRADE CARDS CATS BREED KATZEN OF WORLD PERSIAN ETC. $20.00

POKEMON Persian trading card $2.31

3251 Hager Bro. rug seller trade card Lancaster PA Whittall Anglo Persian carpet $16.00

game part CAT-OPOLY monopoly property trading cards graphic version replacement $4.24

game part CAT-OPOLY monopoly property trading cards photo version replacement $4.24

Full Set of Lime Rock Heroes of The Persian Gulf Trading Cards 1991 Limited Ed. $5.99

Vict Trade Card PERSIAN BALM Sledding Scene w/ Children & Dog Pittsburgh PA $15.00

Pokemon Trading Card Game ~ Stage 1 Cards Persian $3.00

game part Monopoly: Cat Lovers Edition property trading cards replacement $4.24

Vintage Playing Card White Persian Cat Blue Background Single Swap Trading $3.99

POKEMON Persian Cat Japan Promo trading card + Comic Book 1999 New sealed! $22.49

1991 Lime Rock Heroes of the Persian Gulf Trading Card Factory Set $3.74

1991 HEROES OF THE PERSIAN GULF DESERT STORM 110 TRADING CARD SET Factory Sealed $14.95

James Buchan – Persian Bride (2011) – Used – Trade Clot $1.99

Tfh – Persian Cats (1990) – Used – Trade Cloth (Hardcov $2.99

James Buchan – Persian Bride (2002) – Used – Trade Pape $1.99

Tom Holland – Persian Fire (2007) – New – Trade Paper ( $11.44

Elaine Sciolino – Persian Mirrors (2001) – Used – Trade $1.99

Elaine Sciolino – Persian Mirrors (2010) – Used – Trade $4.06

Nahid Rachlin – Persian Girls (2011) – Used – Trade Pap $1.99

1963 The Port of Mombasa Kenya Brings many Persian Gulf Trading Dhows Wire Photo $29.88

Nahid Rachlin – Persian Girls (2011) – Used – Trade Clo $1.99

1938 Lithograph Map Trade Routes India Levant Indian Ocean Red Sea Persian Gulf $67.95

Pokemon Persian Game Trading Card $3.25

DOG Saluki Persian Greyhound Pair, Trading Card, 1940 $9.99

CAT Persian Gray, Lovely Trading Card, 1950s $7.99

CAT Persian Gray Longhaired, Antique 1930 Trading Card $9.99

CAT 3 Longhair Persian, Real Photo Trading Card, 1930s $8.99

India Vintage Trade Label PERSIAN KING 21138 $75.00

1970 Press Photo Persian Cat, Piccadilly Hotel, British Pet Trade Winter Show $27.88

NWT WEBKINZ PERSIAN CAT w/ 1 WEBKINZ Trading Cards pck $16.19

FACTORY SET OF HEROES OF THE PERSIAN GULF LIMITED ED NUMBERED SET TRADING CARDS $4.99

Moda * TRADE WINDS * Persian Rose 11457 14 By The Yard Quilt Fabric $9.45

Persian # 42/64 – Jungle Set – Pokemon Trading Card – Near Mint Condition ! $1.31

TB Trading Plush Cat Kitten Persian 10″ Cuddle Blue Eyes $7.00