From Our Own Correspondent - Russia and the Paraguay/ Bolivia border

Alan Johnston presents insight, wit and analysis from BBC correspondents around the world. In this edition, Judith Pallot on Russia's enduring network of penal colonies and Jonathan Fryer on the unexpected sights and companions he met on a long bus trip in South America.

Soviet roots of Russia's penal colonies

As grim as anything to emerge from the story of the Soviet Union was its prison system. Millions of criminals and political prisoners were exiled to the network of labour camps that became known as "the gulag". They endured appalling conditions, and many never returned.

But the Russian people have lived through huge change in recent decades. The gulag may now be a thing of the past, but as Judith Pallot explains, in the prison system of the new Russia, there remain bleak echoes of the Soviet past.

Well off the beaten track into Bolivia

In the rich world these days, a lot of travel is fairly unremarkable. Identical-looking aeroplanes shuttle between indentical-looking airports. But for millions of people in poorer countries, travel is still often long and hard.

As Jonathan Fryer found out when he set off from Paraguay towards Bolivia, these journeys are often a lot more unpredictable and adventurous ... and you may end up in unexpected company.